Equity and Capital - Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Document Fiscal Year Focus	2017
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	$ 10,931	$ 50,910	$ 8,995
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning of Period	(18,327)	(58,650)	(57,748)
Other Comprehensive Income (Loss), before Reclassifications, before Tax	1,134	(10,587)	(9,897)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	10,931	50,910	8,995
Current period other comprehensive income, net	12,065	40,323	(902)
Accumulated Other Comprehensive Income (Loss), Net of Tax, End of Period	(6,262)	(18,327)	(58,650)
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
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	(19)	(43)	0
Other Comprehensive Income (Loss), before Reclassifications, before Tax	(8)	24	(43)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0	0	0
Current period other comprehensive income, net	(8)	24	(43)
Accumulated Other Comprehensive Income (Loss), Net of Tax, End of Period	(27)	(19)	(43)
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	10,931	50,910	8,995
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning of Period	(18,346)	(58,693)	(57,748)
Other Comprehensive Income (Loss), before Reclassifications, before Tax	1,126	(10,563)	(9,940)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	10,931	50,910	8,995
Current period other comprehensive income, net	12,057	40,347	(945)
Accumulated Other Comprehensive Income (Loss), Net of Tax, End of Period	(6,289)	(18,346)	(58,693)
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Noncontrolling Interest [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	172	229	157
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning of Period	(301)	(785)	(750)
Other Comprehensive Income (Loss), before Reclassifications, before Tax	17	255	(192)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	172	229	157
Current period other comprehensive income, net	189	484	(35)
Accumulated Other Comprehensive Income (Loss), Net of Tax, End of Period	(112)	(301)	(785)
Accumulated Net Investment Gain (Loss) Attributable to Noncontrolling Interest [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
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]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	172	229	157
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning of Period	(301)	(785)	(750)
Other Comprehensive Income (Loss), before Reclassifications, before Tax	17	255	(192)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	172	229	157
Current period other comprehensive income, net	189	484	(35)
Accumulated Other Comprehensive Income (Loss), Net of Tax, End of Period	(112)	(301)	(785)
AOCI Including Portion Attributable to Noncontrolling Interest [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	11,103	51,139	9,152
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning of Period	(18,647)	(59,478)	(58,498)
Other Comprehensive Income (Loss), before Reclassifications, before Tax	1,143	(10,308)	(10,132)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	11,103	51,139	9,152
Current period other comprehensive income, net	12,246	40,831	(980)
Accumulated Other Comprehensive Income (Loss), Net of Tax, End of Period	(6,401)	(18,647)	(59,478)
Accumulated Net Gain (Loss) from Cash Flow Hedges Including Portion Attributable to Noncontrolling Interest [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	11,103	51,139	9,152
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	$ 11,103	$ 51,139	$ 9,152