Equity (Detail) - Share Repurchase Program and Share Repurchase Activity - USD ($)	1 Months Ended	3 Months Ended		9 Months Ended
	Jan. 31, 2016	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Stockholders' Equity Note [Abstract]
Stock repurchase program, authorized amount		$ 1,200,000,000.0		$ 1,200,000,000.0
Stock repurchase program, remaining authorized repurchase amount		$ 1,110,000,000.00		$ 1,110,000,000.00
Number of shares repurchased (in shares)		9,882	210,012	542,792	5,538,612
Cash paid for repurchased shares during the quarter	$ 7,200,000	$ 922,000	$ 11,558,000	$ 52,889,000	$ 453,000,000
Treasury stock, average price paid per share (in dollars per share)		$ 93.33	$ 83.79	$ 84.17	$ 82.40