Borrowings - Components of Borrowings (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Debt outstanding	$ 2,664,850	$ 2,533,212
Less: Debt discount and issuance costs	(46,468)	(59,556)
Total	2,618,382	2,473,656
Term Loan
Debt Instrument [Line Items]
Debt outstanding	430,000	740,551
Convertible Senior Notes
Debt Instrument [Line Items]
Debt outstanding	632,500	632,500
Revolving Credit Facility \| Line of Credit
Debt Instrument [Line Items]
Debt outstanding	$ 1,602,350	$ 1,160,161

Amount of unamortized debt discount (premium) and debt issuance costs.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)(2)
-URI http://asc.fasb.org/extlink&oid=109500613&loc=SL6031897-161870

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28555-108399

Name:	us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant