Long-Term Debt (Senior Notes Due 2023) (Details)	May 15, 2018
2023 Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price, Percentage	102.438%

Percentage price of original principal amount of debt at which debt can be redeemed by the issuer.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-Subparagraph e
-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

Name:	us-gaap_DebtInstrumentRedemptionPricePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration