Stockholders' Equity - AOCI (Details) - USD ($) $ in Thousands	3 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019
AOCI Attributable to Parent, Net of Tax [Roll Forward]
AOCI, beginning balance			$ 2,119,022
Other comprehensive loss before reclassification	$ 17,461	$ (16,324)
Amounts reclassified from AOCI	(1,748)	84,269
Other comprehensive income (loss)	15,713	67,945	(70,999)	$ 3,368	$ 12,427	$ 13,519
AOCI, ending balance	1,703,385
OP
AOCI Attributable to Noncontrolling Interest, Net of Tax [Abstract]
Other comprehensive income (loss) before reclassification	361	(613)
Amounts reclassified from AOCI	(42)	2,016
Other comprehensive income (loss)	319	1,403	(1,702)	80	297	324
Investment Entities
AOCI Attributable to Noncontrolling Interest, Net of Tax [Abstract]
Other comprehensive income (loss)		257	0	915
Accumulated Other Comprehensive Income
AOCI Attributable to Parent, Net of Tax [Roll Forward]
AOCI, beginning balance	25,240	(42,705)	28,294	25,547	13,120	(399)
AOCI, ending balance	40,953	25,240	(42,705)	28,915	25,547	13,120
Unrealized gain (loss) on real estate securities, available for sale
AOCI Attributable to Parent, Net of Tax [Roll Forward]
AOCI, beginning balance	0	(57,364)	15,909	15,914	8,235	(1,295)
Other comprehensive loss before reclassification	6,018	(26,905)
Amounts reclassified from AOCI	(1,748)	84,269
Other comprehensive income (loss)	4,270	57,364	(73,273)	4,983	7,679	9,530
AOCI, ending balance	4,270	0	(57,364)	20,897	15,914	8,235
Unrealized gain on net investment hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
AOCI, beginning balance	47,127	47,127	25,872	19,175	18,259	11,037
Other comprehensive loss before reclassification	0	0
Amounts reclassified from AOCI	0	0
Other comprehensive income (loss)	0	0	21,255	12,492	916	7,222
AOCI, ending balance	47,127	47,127	47,127	31,667	19,175	18,259
Foreign currency translation gain (loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
AOCI, beginning balance	(21,887)	(32,468)	(13,487)	(9,542)	(13,374)	(10,141)
Other comprehensive loss before reclassification	11,443	10,581
Amounts reclassified from AOCI	0	0
Other comprehensive income (loss)	11,443	10,581	(18,981)	(14,107)	3,832	(3,233)
AOCI, ending balance	(10,444)	(21,887)	(32,468)	(23,649)	(9,542)	(13,374)
Unrealized gain (loss) on real estate securities, available for sale | OP
AOCI Attributable to Noncontrolling Interest, Net of Tax [Abstract]
AOCI, beginning balance	0	(1,144)	612	380	196	(32)
Other comprehensive income (loss) before reclassification	63	(872)
Amounts reclassified from AOCI	(42)	2,016
Other comprehensive income (loss)	21	1,144	(1,756)	119	184	228
AOCI, ending balance	21	0	(1,144)	499	380	196
Unrealized gain (loss) on real estate securities, available for sale | Investment Entities
AOCI Attributable to Noncontrolling Interest, Net of Tax [Abstract]
AOCI, beginning balance	0	0	0
Other comprehensive income (loss)		0	0	0
AOCI, ending balance	0	0	0
Unrealized gain (loss) on net investment hedges | OP
AOCI Attributable to Noncontrolling Interest, Net of Tax [Abstract]
AOCI, beginning balance	1,402	1,402	893	463	441	268
Other comprehensive income (loss) before reclassification	0	0
Amounts reclassified from AOCI	0	0
Other comprehensive income (loss)	0	0	509	299	22	173
AOCI, ending balance	1,402	1,402	1,402	762	463	441
Unrealized gain (loss) on net investment hedges | Investment Entities
AOCI Attributable to Noncontrolling Interest, Net of Tax [Abstract]
AOCI, beginning balance	0	0	0
Other comprehensive income (loss)		0	0	0
AOCI, ending balance	0	0	0
Foreign currency translation gain (loss) | OP
AOCI Attributable to Noncontrolling Interest, Net of Tax [Abstract]
AOCI, beginning balance	(997)	(1,256)	(801)	(232)	(323)	(246)
Other comprehensive income (loss) before reclassification	298	259
Amounts reclassified from AOCI	0	0
Other comprehensive income (loss)	298	259	(455)	(338)	91	(77)
AOCI, ending balance	(699)	(997)	(1,256)	(570)	(232)	(323)
Foreign currency translation gain (loss) | Investment Entities
AOCI Attributable to Noncontrolling Interest, Net of Tax [Abstract]
AOCI, beginning balance	257	0	0
Other comprehensive income (loss)		257	0	915
AOCI, ending balance	1,172	257	0
AOCI Attributable to Noncontrolling Interest | OP
AOCI Attributable to Noncontrolling Interest, Net of Tax [Abstract]
AOCI, beginning balance	405	(998)	704	611	314	(10)
AOCI, ending balance	724	405	(998)	$ 691	$ 611	$ 314
AOCI Attributable to Noncontrolling Interest | Investment Entities
AOCI Attributable to Noncontrolling Interest, Net of Tax [Abstract]
AOCI, beginning balance	257	0	0
AOCI, ending balance	$ 1,172	$ 257	$ 0