Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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)(1)
-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 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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

Debt - Debt Covenants (Narrative) (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017	Apr. 28, 2016	Aug. 31, 2015	Aug. 05, 2015
Debt Instrument [Line Items]
Debt, carrying amount	$ 975,000,000	$ 1,028,375,000
Term Credit Agreement
Debt Instrument [Line Items]
Debt, carrying amount	350,000,000	350,000,000
Incremental Term Loan Agreement
Debt Instrument [Line Items]
Debt, carrying amount	$ 300,000,000	$ 300,000,000	$ 300,000,000
Term Loan Facility \| Term Credit Agreement
Debt Instrument [Line Items]
Debt, carrying amount					$ 350,000,000
Maximum borrowing capacity					$ 350,000,000
Revolving credit facility
Debt Instrument [Line Items]
Maximum borrowing capacity				$ 200,000,000