Convertible Senior Notes - Schedule of Note Hedges (Details) - USD ($) $ in Thousands	6 Months Ended
Jun. 30, 2017	Jun. 30, 2016
Derivative [Line Items]
Purchase	$ 128,017	$ 0
2022 Note Hedge
Derivative [Line Items]
Purchase	$ 128,017
Shares	5,806,936
2018 Note Hedge
Derivative [Line Items]
Purchase	$ 135,815
Shares	7,783,023

The cash outflow for a financial contract that meets the hedge criteria as either cash flow hedge, fair value hedge or hedge of net investment in foreign operations.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 27
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3581-108585

Name:	us-gaap_PaymentsForHedgeFinancingActivities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration