Common Stock Repurchase Program (Details) - USD ($)	3 Months Ended
	Jun. 30, 2018	Jul. 01, 2017	May 16, 2018	Mar. 31, 2018	May 16, 2016
Accelerated Share Repurchases [Line Items]
Incremental Common Shares Attributable to Dilutive Effect of Conversion of Debt Securities		6,000,000
Preferred stock, shares issued (none issued)	0			0
Preferred Stock, Shares Outstanding	0			0
Stock Repurchased and Retired During Period, Value	$ 136,800,000	$ 67,100,000
Treasury shares	0			0
Stock Repurchased During Period, Shares	(2,100,000)	(1,000,000)
Repurchase Program Two Thousand Sixteen [Member] [Domain]
Accelerated Share Repurchases [Line Items]
Amount authorized for common stock repurchase					$ 1,000,000,000.0
Stock Repurchased During Period, Value	$ 929,400,000
Total amount available for future repurchases	$ 70,600,000
Repurchase Program Two Thousand Eighteen [Domain]
Accelerated Share Repurchases [Line Items]
Amount authorized for common stock repurchase			$ 500,000,000.0