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

Long-Term Debt - Senior Notes (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018	Dec. 19, 2018	Apr. 04, 2017
Long-Term Debt
Face amount of debt issuance			$ 250,000,000.0
Interest rate			5.125%
Senior Notes 5.50 Percent Due 2025
Long-Term Debt
Face amount of debt issuance	$ 300,000,000.0			$ 300,000,000.0
Interest rate	5.50%	5.50%		5.50%