Stockholders' Equity - AOCI (Details) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	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	$ (26,905)
Amounts reclassified from AOCI	84,269
Other comprehensive income (loss)	67,945	(70,999)	$ 12,427	$ 13,519
AOCI, ending balance	1,679,907
OP
AOCI Attributable to Noncontrolling Interest, Net of Tax [Abstract]
Other comprehensive income before reclassification	(872)
Amounts reclassified from AOCI	2,016
Other comprehensive income (loss)	1,403	(1,702)	297	324
Investment Entities
AOCI Attributable to Noncontrolling Interest, Net of Tax [Abstract]
Other comprehensive income (loss)	257	0
Accumulated Other Comprehensive Income
AOCI Attributable to Parent, Net of Tax [Roll Forward]
AOCI, beginning balance	(42,705)	28,294	13,120	(399)
AOCI, ending balance	25,240	(42,705)	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	(57,364)	15,909	8,235	(1,295)
Other comprehensive loss before reclassification	(26,905)
Amounts reclassified from AOCI	84,269
Other comprehensive income (loss)	57,364	(73,273)	7,679	9,530
AOCI, ending balance	0	(57,364)	15,914	8,235
Unrealized gain on net investment hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
AOCI, beginning balance	47,127	25,872	18,259	11,037
Other comprehensive loss before reclassification	0
Amounts reclassified from AOCI	0
Other comprehensive income (loss)	0	21,255	916	7,222
AOCI, ending balance	47,127	47,127	19,175	18,259
Foreign currency translation gain (loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
AOCI, beginning balance	(32,468)	(13,487)	(13,374)	(10,141)
Other comprehensive loss before reclassification	0
Amounts reclassified from AOCI	0
Other comprehensive income (loss)	10,581	(18,981)	3,832	(3,233)
AOCI, ending balance	(21,887)	(32,468)	(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	(1,144)	612	196	(32)
Other comprehensive income before reclassification	(872)
Amounts reclassified from AOCI	2,016
Other comprehensive income (loss)	1,144	(1,756)	184	228
AOCI, ending balance	0	(1,144)	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
Other comprehensive income (loss)	0	0
AOCI, ending balance	0	0
Unrealized gain (loss) on net investment hedges | OP
AOCI Attributable to Noncontrolling Interest, Net of Tax [Abstract]
AOCI, beginning balance	1,402	893	441	268
Other comprehensive income before reclassification	0
Amounts reclassified from AOCI	0
Other comprehensive income (loss)	0	509	22	173
AOCI, ending balance	1,402	1,402	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
Other comprehensive income (loss)	0	0
AOCI, ending balance	0	0
Foreign currency translation gain (loss) | OP
AOCI Attributable to Noncontrolling Interest, Net of Tax [Abstract]
AOCI, beginning balance	(1,256)	(801)	(323)	(246)
Other comprehensive income before reclassification	0
Amounts reclassified from AOCI	0
Other comprehensive income (loss)	259	(455)	91	(77)
AOCI, ending balance	(997)	(1,256)	(232)	(323)
Foreign currency translation gain (loss) | Investment Entities
AOCI Attributable to Noncontrolling Interest, Net of Tax [Abstract]
AOCI, beginning balance	0	0
Other comprehensive income (loss)	257	0
AOCI, ending balance	257	0
AOCI Attributable to Noncontrolling Interest | OP
AOCI Attributable to Noncontrolling Interest, Net of Tax [Abstract]
AOCI, beginning balance	(998)	704	314	(10)
AOCI, ending balance	405	(998)	$ 611	$ 314
AOCI Attributable to Noncontrolling Interest | Investment Entities
AOCI Attributable to Noncontrolling Interest, Net of Tax [Abstract]
AOCI, beginning balance	0	0
AOCI, ending balance	$ 257	$ 0