New Accounting Standards New Accounting Standards (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Accounting Changes and Error Corrections [Abstract]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification			$ 2,573		$ 156,400
Income Tax Effects Allocated Directly to Equity, Cumulative Effect of Change in Accounting Principle					17,700
Effective Income Tax Rate Reconciliation, Equity in Earnings (Losses) of Unconsolidated Subsidiary, Amount	$ 817	$ 2,762	$ 5,067	$ 7,226	10,500
Contractual Obligation					$ 38,200

No definition available.

Name:	us-gaap_AccountingChangesAndErrorCorrectionsAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of contractual obligation, including but not limited to, long-term debt, capital lease obligations, operating lease obligations, purchase obligations, and other commitments.

+ References

No definition available.

+ Details

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

- Definition

Amount of cumulative tax effect on beginning retained earnings from change in accounting principle.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 20
-Section 45
-Paragraph 11
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109238882&loc=d3e39076-109324

+ Details

Name:	us-gaap_IncomeTaxEffectsAllocatedDirectlyToEquityCumulativeEffectOfChangeInAccountingPrinciple
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to equity in earnings (loss) of unconsolidated subsidiaries exempt from income taxes.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32687-109319

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 13
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32698-109319

+ Details

Name:	us-gaap_IncomeTaxReconciliationEquityInEarningsLossesOfUnconsolidatedSubsidiary
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Represents the quantification of the effect of adopting the new accounting standard or change in accounting principle expected by the entity to have a significant effect on the entity's financial statements.

+ References

No definition available.

+ Details

Name:	us-gaap_NewAccountingPronouncementOrChangeInAccountingPrincipleEffectOfAdoptionQuantification
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration