Basis of Presentation (Narrative) (Details) $ in Thousands		3 Months Ended
		Mar. 31, 2018 USD ($) segment	Mar. 31, 2017 USD ($)	Dec. 31, 2017 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of reportable segments | segment		4
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other liabilities		$ 207,866		$ 437,600
Distributed earnings from unconsolidated subsidiaries		7,018	$ 10,893
Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclassification from AOCI to retained earnings for stranded tax effects		(3,400)
Accumulated Other Comprehensive Income (Loss)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclassification from AOCI to retained earnings for stranded tax effects		$ 3,400
Accounting Standards Update 2016-15
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Distributions from unconsolidated subsidiaries, investing activities			(10,900)
Distributed earnings from unconsolidated subsidiaries			$ 10,900
Accounting Standards Update 2016-01
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative-effect adjustment adoption of ASU	[1]			8,334
Accounting Standards Update 2016-01 | Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative-effect adjustment adoption of ASU	[1]			$ 8,334

[1] See Note 1 for discussion of accounting guidance adopted during the period.