Income Taxes - Reconciliation of Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at January 1	$ 7,090	$ 6,559	$ 11,851
Additions based on tax positions related to the current year	969	1,120	638
Additions for tax positions of prior years	542	132	121
Reductions for tax positions of prior years	(80)	(255)	(3,691)
Settlement of tax audits	0	0	(258)
Reductions due to lapsed statute of limitations	(265)	(466)	(2,102)
Balance at December 31	$ 8,256	$ 7,090	$ 6,559