Face (par) amount of debt instrument at time of issuance.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Debt Senior Unsecured Notes (Details) - USD ($)	Mar. 31, 2019	Dec. 31, 2018	Oct. 04, 2018	Aug. 21, 2018
Debt Instrument [Line Items]
Debt issued	$ 1,038,229,000	$ 1,037,837,000
Senior Notes \| 2026 Notes Offering
Debt Instrument [Line Items]
Debt issued				$ 750,000,000
Interest rate				5.875%
Senior Notes \| Additional 2026 Notes
Debt Instrument [Line Items]
Debt issued			$ 300,000,000