Equity and Capital - Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Document Fiscal Year Focus	2018
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets		$ 12
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	$ 5,314	10,931	$ 50,910
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning of Period	(6,262)	(18,327)	(58,650)
Other Comprehensive Income (Loss), before Reclassifications, before Tax	131	1,134	(10,587)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	5,314	10,931	50,910
Current period other comprehensive income, net	5,445	12,065	40,323
Accumulated Other Comprehensive Income (Loss), Net of Tax, End of Period	(805)	(6,262)	(18,327)
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets		0
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0	0	0
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning of Period	(27)	(19)	(43)
Other Comprehensive Income (Loss), before Reclassifications, before Tax	(95)	(8)	24
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0	0	0
Current period other comprehensive income, net	(95)	(8)	24
Accumulated Other Comprehensive Income (Loss), Net of Tax, End of Period	(122)	(27)	(19)
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets		12
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	5,314	10,931	50,910
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning of Period	(6,289)	(18,346)	(58,693)
Other Comprehensive Income (Loss), before Reclassifications, before Tax	36	1,126	(10,563)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	5,314	10,931	50,910
Current period other comprehensive income, net	5,350	12,057	40,347
Accumulated Other Comprehensive Income (Loss), Net of Tax, End of Period	(927)	(6,289)	(18,346)
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Noncontrolling Interest [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets		2
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	28	172	229
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning of Period	(112)	(301)	(785)
Other Comprehensive Income (Loss), before Reclassifications, before Tax	271	17	255
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	28	172	229
Current period other comprehensive income, net	299	189	484
Accumulated Other Comprehensive Income (Loss), Net of Tax, End of Period	189	(112)	(301)
Accumulated Net Investment Gain (Loss) Attributable to Noncontrolling Interest [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets		0
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0	0	0
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning of Period	0	0	0
Other Comprehensive Income (Loss), before Reclassifications, before Tax	0	0	0
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0	0	0
Current period other comprehensive income, net	0	0	0
Accumulated Other Comprehensive Income (Loss), Net of Tax, End of Period	0	0	0
AOCI Attributable to Noncontrolling Interest [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets		2
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	28	172	229
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning of Period	(112)	(301)	(785)
Other Comprehensive Income (Loss), before Reclassifications, before Tax	271	17	255
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	28	172	229
Current period other comprehensive income, net	299	189	484
Accumulated Other Comprehensive Income (Loss), Net of Tax, End of Period	189	(112)	(301)
AOCI Including Portion Attributable to Noncontrolling Interest [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets		14
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	5,342	11,103	51,139
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning of Period	(6,401)	(18,647)	(59,478)
Other Comprehensive Income (Loss), before Reclassifications, before Tax	307	1,143	(10,308)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	5,342	11,103	51,139
Current period other comprehensive income, net	5,649	12,246	40,831
Accumulated Other Comprehensive Income (Loss), Net of Tax, End of Period	(738)	(6,401)	$ (18,647)
Accounting Standards Update 2017-12 [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning of Period	(6,250)
Accumulated Other Comprehensive Income (Loss), Net of Tax, End of Period		(6,250)
Accounting Standards Update 2017-12 [Member] | Accumulated Net Unrealized Investment Gain (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning of Period	(27)
Accumulated Other Comprehensive Income (Loss), Net of Tax, End of Period		(27)
Accounting Standards Update 2017-12 [Member] | Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning of Period	(6,277)
Accumulated Other Comprehensive Income (Loss), Net of Tax, End of Period		(6,277)
Accounting Standards Update 2017-12 [Member] | Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Noncontrolling Interest [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning of Period	(110)
Accumulated Other Comprehensive Income (Loss), Net of Tax, End of Period		(110)
Accounting Standards Update 2017-12 [Member] | Accumulated Net Investment Gain (Loss) Attributable to Noncontrolling Interest [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning of Period	0
Accumulated Other Comprehensive Income (Loss), Net of Tax, End of Period		0
Accounting Standards Update 2017-12 [Member] | AOCI Attributable to Noncontrolling Interest [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning of Period	(110)
Accumulated Other Comprehensive Income (Loss), Net of Tax, End of Period		(110)
Accounting Standards Update 2017-12 [Member] | AOCI Including Portion Attributable to Noncontrolling Interest [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning of Period	$ (6,387)
Accumulated Other Comprehensive Income (Loss), Net of Tax, End of Period		$ (6,387)