Quarterly report pursuant to Section 13 or 15(d)

Income Taxes - Components of Provision (Benefit) for Income Taxes and Earnings before Income Taxes (Detail)

v2.4.0.8
Income Taxes - Components of Provision (Benefit) for Income Taxes and Earnings before Income Taxes (Detail) (USD $)
In Thousands, unless otherwise specified
3 Months Ended 9 Months Ended
Sep. 30, 2013
Sep. 30, 2012
Sep. 30, 2013
Sep. 30, 2012
Provision Benefit For Income Taxes [Line Items]        
Computed expected tax expense $ 4,504 $ 3,967 $ 10,480 $ 9,228
State taxes (net of federal tax effect) 630 555 1,467 1,292
Permanent differences (15) (24) 42 (17)
Provision for income taxes 5,597 4,931 13,025 11,469
Tax-sharing agreement [Member]
       
Provision Benefit For Income Taxes [Line Items]        
Difference due to tax-sharing rate $ 478 $ 433 $ 1,036 $ 966