Loans - Activity in Portfolio (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Activity in allowance for loan losses
Credit loss allowance at the beginning of the period	$ 33,611
Credit loss allowance at the end of the period	97,312
Activity in loan portfolio
Balance at the beginning of the period	11,470,224	$ 9,794,254
Acquisitions/origination/additional funding	1,898,905	2,027,669
Capitalized Interest	36,072	22,137
Basis of loans sold	(789,863)	(1,127,201)
Loan maturities/principal repayments	(796,323)	(630,965)
Discount accretion/premium amortization	12,080	7,526
Changes in fair value	(16,134)	11,266
Unrealized foreign currency translation (loss) gain	(87,319)	14,208
Credit loss provision, net	(43,332)	(763)
Loan foreclosure		(8,963)
Transfer to/from other asset classifications		47
Balance at the end of the period	11,663,870	10,109,215
ASU 2016-13
Activity in loan portfolio
Loan maturities/principal repayments	(20,440)
Total loans held-for-investment
Activity in allowance for loan losses
Credit loss allowance at the beginning of the period	33,415
Credit loss allowance at the end of the period	97,187
Loans held-for-sale
Activity in loan portfolio
Balance at the beginning of the period	884,150	1,187,552
Acquisitions/origination/additional funding	646,160	747,265
Basis of loans sold	(789,259)	(733,645)
Loan maturities/principal repayments	(20,680)	(22,845)
Discount accretion/premium amortization	110
Changes in fair value	9,485	11,266
Unrealized foreign currency translation (loss) gain	(4,056)	2,119
Credit loss provision, net		(774)
Transfer to/from other asset classifications	449,024	(46,448)
Balance at the end of the period	1,174,934	1,144,490
Funded Loan Commitments [Member]
Activity in allowance for loan losses
Credit loss allowance at the beginning of the period	33,611
Credit loss provision, net	43,332
Charge-offs	(71)
Credit loss allowance at the end of the period	97,312
Funded Loan Commitments [Member] | ASU 2016-13
Activity in allowance for loan losses
Provision for impaired loans	20,440
Unfunded lending commitments | ASU 2016-13
Activity in allowance for loan losses
Credit loss provision, net	4,430
Provision for impaired loans	10,553
Credit loss allowance at the end of the period	14,983
Unfunded commitments	(2,645,420)
Commercial Portfolio Segment | Total loans held-for-investment
Activity in allowance for loan losses
Credit loss allowance at the beginning of the period	33,415
Credit loss allowance at the end of the period	81,054
Activity in loan portfolio
Balance at the beginning of the period	8,517,054	7,075,577
Acquisitions/origination/additional funding	1,089,096	1,005,325
Capitalized Interest	36,072	22,137
Basis of loans sold		(393,556)
Loan maturities/principal repayments	(689,972)	(251,530)
Discount accretion/premium amortization	11,559	7,043
Unrealized foreign currency translation (loss) gain	(83,263)	12,089
Credit loss provision, net	(37,527)	11
Loan foreclosure		(8,963)
Transfer to/from other asset classifications		46,495
Balance at the end of the period	8,832,907	7,514,628
Commercial Portfolio Segment | Total loans held-for-investment | ASU 2016-13
Activity in loan portfolio
Loan maturities/principal repayments	(10,112)
Commercial Portfolio Segment | Funded Loan Commitments [Member]
Activity in allowance for loan losses
Credit loss allowance at the beginning of the period	33,415
Credit loss provision, net	37,527
Credit loss allowance at the end of the period	81,054
Commercial Portfolio Segment | Funded Loan Commitments [Member] | ASU 2016-13
Activity in allowance for loan losses
Provision for impaired loans	10,112
Commercial Portfolio Segment | Unfunded lending commitments | ASU 2016-13
Activity in allowance for loan losses
Credit loss provision, net	(195)
Provision for impaired loans	8,348
Credit loss allowance at the end of the period	8,153
Unfunded commitments	(2,447,330)
Infrastructure Portfolio Segment | Total loans held-for-investment
Activity in allowance for loan losses
Credit loss allowance at the end of the period	16,133
Activity in loan portfolio
Balance at the beginning of the period	1,397,448	1,456,779
Acquisitions/origination/additional funding	62,929	275,079
Loan maturities/principal repayments	(37,051)	(281,898)
Discount accretion/premium amortization	411	137
Credit loss provision, net	(5,805)
Transfer to/from other asset classifications	(26,333)
Balance at the end of the period	1,381,271	1,450,097
Infrastructure Portfolio Segment | Total loans held-for-investment | ASU 2016-13
Activity in loan portfolio
Loan maturities/principal repayments	(10,328)
Infrastructure Portfolio Segment | Loans held-for-sale
Activity in allowance for loan losses
Credit loss allowance at the beginning of the period	196
Credit loss allowance at the end of the period	125
Infrastructure Portfolio Segment | Funded Loan Commitments [Member]
Activity in allowance for loan losses
Credit loss provision, net	5,805
Credit loss allowance at the end of the period	16,133
Infrastructure Portfolio Segment | Funded Loan Commitments [Member] | ASU 2016-13
Activity in allowance for loan losses
Provision for impaired loans	10,328
Infrastructure Portfolio Segment | Unfunded lending commitments | ASU 2016-13
Activity in allowance for loan losses
Credit loss provision, net	2,645
Provision for impaired loans	2,205
Credit loss allowance at the end of the period	4,850
Unfunded commitments	(180,829)
Loans Held For Sale Infrastructure | Funded Loan Commitments [Member]
Activity in allowance for loan losses
Credit loss allowance at the beginning of the period	196
Charge-offs	(71)
Credit loss allowance at the end of the period	125
Loans Held For Sale Infrastructure | Unfunded lending commitments | ASU 2016-13
Activity in allowance for loan losses
Credit loss provision, net	1,980
Credit loss allowance at the end of the period	1,980
Unfunded commitments	(17,261)
Residential Portfolio Segment | Total loans held-for-investment
Activity in loan portfolio
Balance at the beginning of the period	671,572	74,346
Acquisitions/origination/additional funding	100,720
Basis of loans sold	(604)
Loan maturities/principal repayments	(48,620)	(74,692)
Discount accretion/premium amortization		$ 346
Changes in fair value	(25,619)
Transfer to/from other asset classifications	(422,691)
Balance at the end of the period	$ 274,758