Subsequent Events - Narrative (Details) - Subsequent Event	Feb. 27, 2018 USD ($) $ / shares	Feb. 22, 2018 USD ($) $ / shares	Feb. 23, 2018 USD ($)
Subsequent Event [Line Items]
Proceeds from issuance of warrants	$ 52,400,000
Aggregate amount paid for cost of Note Hedge	80,000,000
Warrant strike price (in dollars per share) | $ / shares		$ 68.06
Strike price of warrants, premium percentage		90.00%
Initial Notes | Senior Notes
Subsequent Event [Line Items]
Aggregate principal amount		$ 300,000,000	$ 345,000,000
Net proceeds	$ 334,000,000
Interest rate	0.25%
Initial conversion rate of common stock	0.0206795
Conversion price (in dollars per share) | $ / shares	$ 48.36
Redemption price percentage	100.00%
Additional Notes | Senior Notes
Subsequent Event [Line Items]
Aggregate principal amount			$ 45,000,000