Quarterly report pursuant to Section 13 or 15(d)

Investments in Marketable Securities - Additional Information (Detail)

v3.5.0.2
Investments in Marketable Securities - Additional Information (Detail) - USD ($)
3 Months Ended 9 Months Ended
Sep. 30, 2016
Sep. 30, 2015
Sep. 30, 2016
Sep. 30, 2015
Schedule of Available-for-sale Securities [Line Items]        
Gross realized loss $ 0 $ 0 $ 155,000 $ 3,000
Sale of Available-For-Sale, Marketable Security that No Longer Met Investment Policy [Member]        
Schedule of Available-for-sale Securities [Line Items]        
Gross realized loss     $ 152,000