Income Taxes - Unrecognized Tax Benefits for Permanent and Temporary Book/Tax Differences for Continuing Operations, Exclusive of Interest (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning balance	$ 3,197	$ 5,843	$ 8,314
Settlements for tax positions of prior years	(139)	(518)	(367)
Additions for tax positions of the current year	47	714
Additions for tax positions of prior years	438	1,518	1,151
Reductions for tax positions of prior years			(942)
Statute lapses	(1,260)	(4,360)	(2,313)
Ending balance	$ 2,283	$ 3,197	$ 5,843