Equity (Detail) - Share Repurchase Activity - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended
	Jan. 31, 2016	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Stockholders' Equity Note [Abstract]
Number of shares repurchased (in shares)		66,087	1,244,010	532,910	5,328,600
Cash paid for repurchased shares during the quarter	$ 7,200	$ 6,480	$ 117,400	$ 51,967	$ 441,442