Stock Repurchase Program (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended					69 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Sep. 30, 2016
Equity [Abstract]
Number of shares repurchased as part of stock repurchase programs	360,000	4,994,578	15,812,566	7,185,257	1,150,000	29,502,401
Cost of shares repurchased	$ 12,391	$ 193,434	$ 436,419	$ 125,341	$ 19,138	$ 786,723
Weighted Average Price	$ 34.42	$ 38.73	$ 27.60	$ 17.44	$ 16.64	$ 26.67