Schedule II - Valuation and Qualifying Accounts (Detail) - Valuation Allowances for Deferred Tax Assets [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Valuation And Qualifying Accounts Disclosure [Line Items]
Balance at beginning of period	$ 43,173	$ 36,645	$ 23,964
Additions/charged to expense	4,803	6,528	12,681
Balance at end of period	$ 47,976	$ 43,173	$ 36,645