Annual report pursuant to Section 13 and 15(d)

Stock-Based Compensation Plans - Outstanding Awards Under 2013 Omnibus Equity Incentive Plan (Detail)

v3.20.4
Stock-Based Compensation Plans - Outstanding Awards Under 2013 Omnibus Equity Incentive Plan (Detail) - USD ($)
$ / shares in Units, $ in Thousands
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Nonvested shares at beginning 800,075 891,575 981,855
Granted 434,705 355,130 258,078
Vested (284,503) (400,616) (333,724)
Transferred 0 0 0
Forfeited/canceled (31,898) (46,014) (14,634)
Nonvested shares at ending 918,379 800,075 891,575
Unrecognized stock-based compensation expense as of December 31, 2020 $ 25,426    
Weighted average remaining vesting period (years) as of December 31, 2020 3 years 5 months 1 day    
Nonvested weighted average grant date fair value per share, beginning balance $ 33.91 $ 27.59 $ 23.90
Weighted average grant date fair value per share, Granted 32.80 38.51 34.94
Weighted average grant date fair value per share, Vested 32.74 24.29 22.31
Weighted average grant date fair value per share, Transferred 33.67 29.68 30.69
Weighted average grant date fair value per share, Forfeited/canceled 34.49 30.65 30.17
Nonvested weighted average grant date fair value per share, ending balance $ 33.73 $ 33.91 $ 27.59
Restricted Stock Awards [Member] | Non-Employee Directors [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Nonvested shares at beginning 17,480 27,096 30,732
Granted 19,516 12,806 12,852
Vested (20,268) (22,422) (16,488)
Transferred 0 0 0
Forfeited/canceled 0 0 0
Nonvested shares at ending 16,728 17,480 27,096
Unrecognized stock-based compensation expense as of December 31, 2020 $ 153    
Weighted average remaining vesting period (years) as of December 31, 2020 4 months 2 days    
Restricted Stock Units [Member] | Employees [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Nonvested shares at beginning 525,115 471,782 500,859
Granted 322,910 260,274 142,760
Vested (170,291) (186,311) (146,122)
Transferred (18,294) (8,136) (23,755)
Forfeited/canceled (21,790) (12,494) (1,960)
Nonvested shares at ending 637,650 525,115 471,782
Unrecognized stock-based compensation expense as of December 31, 2020 $ 17,718    
Weighted average remaining vesting period (years) as of December 31, 2020 3 years 6 months 29 days    
Restricted Stock Units [Member] | Independent Contractors [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Nonvested shares at beginning 257,480 392,697 450,264
Granted 92,279 82,050 102,466
Vested (93,944) (191,883) (171,114)
Transferred 18,294 8,136 23,755
Forfeited/canceled (10,108) (33,520) (12,674)
Nonvested shares at ending 264,001 257,480 392,697
Unrecognized stock-based compensation expense as of December 31, 2020 $ 7,555    
Weighted average remaining vesting period (years) as of December 31, 2020 3 years 1 month 17 days