Equity (Detail) - Share Repurchase Activity (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013		Jun. 30, 2014		Jun. 30, 2013
Stockholders' Equity Note [Abstract]
Number of shares repurchased	1,527,084	[1]	865,325	[1]	4,226,798	[1]	1,842,268	[1]
Cost of repurchased shares	$ 111,598	[2]	$ 49,472	[2]	$ 307,448	[2]	$ 98,000	[2]

[1] The average purchase price for the shares was $69.59 and $70.07 for the three and six months ended June 30, 2014, respectively, and $57.17 and $53.19 for the three and six months ended June 30, 2013, respectively.

[2] The cost of repurchased shares for the six months ended June 30, 2014 includes payment for share repurchase transactions that occurred in late December 2013 but were settled in early January 2014.