Equity (Detail) - Share Repurchase Activity - USD ($) $ in Thousands		1 Months Ended	3 Months Ended		6 Months Ended
		Jan. 31, 2015	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015		Jun. 30, 2014
Stockholders' Equity Note [Abstract]
Number of shares repurchased (in shares)	[1],[2]		1,244,010	1,527,084	5,328,600		4,226,798
Cash paid for repurchased shares during the quarter		$ 2,700	$ 117,400	$ 111,598	$ 441,442	[3]	$ 307,448	[3]

[1] The average cost of the repurchased shares was $84.03 and $82.34 for the three and six months ended June 30, 2015, respectively

[2] These share repurchases were completed under the Company's prior share repurchase authorization, which was fully utilized.

[3] The cash paid for the six months ended June 30, 2015 includes $2.7 million for share repurchase transactions that occurred in late December 2014 and were paid in early January 2015.