Investment in Expedia - Additional Information (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions		1 Months Ended
	Mar. 30, 2017	Apr. 30, 2017	Apr. 27, 2017	Feb. 28, 2017	Mar. 31, 2017	Feb. 28, 2015
Schedule of Equity Method Investments [Line Items]
Proceeds from Dividends Received	$ 6
Expedia
Schedule of Equity Method Investments [Line Items]
Common Stock, Dividends, Per Share, Declared		$ 0.28		$ 0.28
Dividends, Common Stock, Cash	$ 42
Stock Repurchase Program, Number of Shares Authorized to be Repurchased						10.0
Stock Repurchase Program, Remaining Number of Shares Authorized to be Repurchased					6.9
Treasury Stock, Shares, Acquired			0.1
Treasury Stock, Value, Acquired, Cost Method			$ 14