Income Taxes - Income Tax Expense (Benefit) Included in Consolidated Statements of Comprehensive Income (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current:
Federal									$ 21,086	$ 18,816	$ 18,079
Foreign									45	42	43
State and local									2,475	2,681	2,694
Total									23,606	21,539	20,816
Deferred:
Federal									(1,086)	4,148	1,060
State and local									768	712	953
Total									(318)	4,860	2,013
Provision for income taxes from continuing operations	$ (3,368)	$ 6,172	$ 4,343	$ 16,141	$ (967)	$ 7,260	$ 5,306	$ 14,800	23,288	26,399	22,829
Operations of discontinued operations:
Current									(418)	(365)	(1,263)
Deferred									(19)	(10)	68
Total									(437)	(375)	(1,195)
Gain on disposal of discontinued operations:
Current											427
Deferred											(344)
Total											83
Total income tax expense from discontinued operations									(437)	(375)	(1,112)
Total income tax expense									$ 22,851	$ 26,024	$ 21,717