Fair Value Measurements - Fair Value by Balance Sheet Grouping (Details) - Fair Value Measurements Using Level 3 [Member] - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Carrying Amount [Member]
Liabilities
Carrying value of debt	$ 2,002,579	$ 2,068,867
Carrying Amount [Member] \| LCIF [Member]
Liabilities
Carrying value of debt	360,657	370,581
Fair Value [Member]
Liabilities
Fair value of debt	1,945,604	2,013,226
Fair Value [Member] \| LCIF [Member]
Liabilities
Fair value of debt	$ 342,989	$ 352,806

Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=77997519&loc=d3e13433-108611

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=77997519&loc=d3e13476-108611

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