XML 64 R49.htm IDEA: XBRL DOCUMENT v3.8.0.1
Commitments and Contingencies - Additional Information (Detail) - USD ($)
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]      
Total rent expense and related taxes and operating expenses, under operating leases $ 1,545,000 $ 6,694,000 $ 7,759,000
Tax reserves, non-income tax related $ 0 $ 0