Share Repurchase Programs (detail) $ in Millions	12 Months Ended
	Dec. 31, 2015 USD ($)
December 16, 2014 [Member]
Schedule Of Share Repurchase Programs [Line Items]
Share Repurchase Authorization Date	Dec. 16, 2014
Amount authorized to be repurchased	$ 1,000.0
Remaining authorized repurchase amount	$ 465.6
December 15, 2015 [Member]
Schedule Of Share Repurchase Programs [Line Items]
Share Repurchase Authorization Date	Dec. 15, 2015
Amount authorized to be repurchased	$ 1,000.0
Remaining authorized repurchase amount	$ 1,000.0