Business and Basis of Presentation - Additional Information (Detail) $ in Thousands	9 Months Ended
	Sep. 30, 2016 USD ($) Segment	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Dec. 31, 2014 USD ($)
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Cash, cash equivalents and restricted cash and investments	$ 406,600
Cash and cash equivalents	395,140	$ 80,304	$ 55,819	$ 73,551
Restricted cash and investments	$ 11,500
Number of operating segments | Segment	1