Net Loss per Share (Details) $ / shares in Units, shares in Thousands, $ in Thousands				1 Months Ended	12 Months Ended
	Nov. 19, 2018 $ / shares shares	Sep. 15, 2017 USD ($) $ / shares shares	Sep. 11, 2017 $ / shares shares	Nov. 30, 2018 USD ($)	Dec. 31, 2018 USD ($) $ / shares shares	Dec. 31, 2017 USD ($) $ / shares shares	Dec. 31, 2016 USD ($) $ / shares shares
Anti-dilutive securities
Capped call transactions paid from net proceeds | $				$ 93,400	$ 93,438	$ 44,160	$ 0
Allocation of undistributed earnings between stock classes, conversion ratio					1
Numerator:
Net loss | $					$ (504,080)	$ (244,614)	$ (194,375)
Denominator:
Weighted average units used for basic and diluted net loss per unit computation (in units) | shares					89,472	86,983	84,977
Net loss per common unit attributable to common unit holders:
Basic and Diluted (in dollars per unit) | $ / shares					$ (5.63)	$ (2.81)	$ (2.29)
3.75% Senior Note Due 2022 | Convertible Debt
Anti-dilutive securities
Capped call transactions paid from net proceeds | $		$ 44,200
Net loss per common unit attributable to common unit holders:
Conversion price (in dollars per share) | $ / shares		$ 104.06
3.75% Senior Note Due 2022 | Convertible Debt | Class A common stock
Net loss per common unit attributable to common unit holders:
Conversion price (in dollars per share) | $ / shares		$ 104.06
Conversion of stock, shares Issued (in shares) | shares		4,100
Cap price per share (in usd per share) | $ / shares			$ 154.16
Capped Call Transaction, shares issued (in shares) | shares			2,800
1.125% 2018 Senior Note Due 2024 | Convertible Debt
Anti-dilutive securities
Capped call transactions paid from net proceeds | $						$ 93,400
1.125% 2018 Senior Note Due 2024 | Convertible Debt | Class A common stock
Net loss per common unit attributable to common unit holders:
Conversion price (in dollars per share) | $ / shares	$ 116.40
Conversion of stock, shares Issued (in shares) | shares	4,900
Cap price per share (in usd per share) | $ / shares	$ 219.63
Capped Call Transaction, shares issued (in shares) | shares	2,600
Common Stock Options, Restricted Stock Options And Restricted Stock Units
Net loss per common unit attributable to common unit holders:
Common stock outstanding that have been excluded from the computation of diluted net loss per share | shares					8,100	7,000	7,300