Fair Value of Financial Instruments - Convertible Note Hedges and Note Hedge Warrants - Change in Level 3 (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2017 USD ($)
Convertible Note Hedge
Change in level 3 assets
Balance at beginning of period	$ 132,521
Change in fair value, recorded as a component of gain (loss) on derivatives	39,359
Balance at end of period	171,880
Note Hedge Warrants
Change in level 3 liabilities
Balance at beginning of period	(113,237)
Change in fair value, recorded as a component of gain (loss) on derivatives	(36,221)
Balance at end of period	$ (149,458)