Subsequent Events Subsequent Events (Details) - Subsequent Event [Member] - USD ($)			10 Months Ended
	Jul. 20, 2018	Jul. 19, 2018	May 20, 2019
Subsequent Event [Line Items]
Sale of stock, consideration received		$ 1,000,000,000
Sale of stock, number of shares issued		10,582,010
Sale of stock, price (in USD per share)		$ 94.50
Accelerated Share Repurchases, Settlement (Payment) or Receipt	$ 1,000,000,000
Accelerated Share Repurchases, Initial Number of Shares	8,244,873
Accelerated Share Repurchases, Initial Price Paid Per Share	$ 97.03
Stock Repurchased and Retired During Period, Value			$ 200,000,000
Minimum [Member]
Subsequent Event [Line Items]
Accelerated Share Repurchase Settlement Period	7 months 15 days
Maximum [Member]
Subsequent Event [Line Items]
Accelerated Share Repurchase Settlement Period	10 months
Initial
Subsequent Event [Line Items]
Stock Repurchased and Retired During Period, Value	$ 800,000,000