Basis of Presentation and Significant Accounting Policies Noncontrolling Interest (Details) $ in Thousands	12 Months Ended
Dec. 31, 2017 USD ($) shares	Dec. 31, 2018 USD ($) shares
Stockholders' Equity Attributable to Noncontrolling Interest \| $	$ 264,110	$ 41,150
Preferred Stock, Shares Outstanding \| shares	0	0
Ambac Assurance Corporation [Member]
Preferred Stock, Shares Outstanding \| shares	26,411	4,115
Preferred Stock, Liquidation Preference, Value \| $	$ 660,275	$ 102,875
London Interbank Offered Rate (LIBOR) [Member]
Dividend Rate on Auction Rate Preferred Shares	200

Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which is directly or indirectly attributable to that ownership interest in subsidiary equity which is not attributable to the parent (that is, noncontrolling interest, previously referred to as minority interest).

Reference 1: 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(a)(24))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.31)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: 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(22))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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Balance Type:	credit
Period Type:	instant