Income Taxes - Unrecognized Tax Benefits (Details) $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($)
Unrecognized tax benefits
Increase in tax positions from the acquisition of a controlling interest in Expedia	$ 220.0
Increases to tax positions related to the current year	1.0
Balance at end of year	221.0
Accrued interest and penalties from unrecognized tax benefits	15.0
Maximum
Unrecognized tax benefits
Unrecognized tax benefit that would impact effective tax rate	$ 181.0