Commercial Mortgage Loans, Subordinate Loans and Other Lending Assets, Net - Allocation of Carrying Value of Loan Portfolio Based on Internal Risk Ratings (Details) $ in Thousands	12 Months Ended
Dec. 31, 2021 USD ($) loan	Dec. 31, 2020 USD ($) loan
Financing Receivable, Credit Quality Indicator [Line Items]
Number of Loans \| loan	67	67
Total	$ 7,890,848	$ 6,535,079
Mortgage loans on real estate, commercial and consumer, percentage of portfolio	100.00%	100.00%
Year 1	$ 2,622,248	$ 469,586
Year 2	644,404	2,661,017
Year 3	2,307,948	1,398,479
Year 4	828,270	999,564
Year 5	648,727	204,129
Prior	839,251	802,304
General CECL Allowance	(33,588)	(38,102)
Total carrying value, net	$ 7,857,260	$ 6,496,977
Weighted Average Risk Rating	3.1	3.1
1
Financing Receivable, Credit Quality Indicator [Line Items]
Number of Loans \| loan	0	0
Total	$ 0	$ 0
Mortgage loans on real estate, commercial and consumer, percentage of portfolio	0.00%	0.00%
Year 1	$ 0	$ 0
Year 2	0	0
Year 3	0	0
Year 4	0	0
Year 5	0	0
Prior	$ 0	$ 0
2
Financing Receivable, Credit Quality Indicator [Line Items]
Number of Loans \| loan	1	1
Total	$ 32,000	$ 32,000
Mortgage loans on real estate, commercial and consumer, percentage of portfolio	0.40%	0.50%
Year 1	$ 0	$ 0
Year 2	0	0
Year 3	0	0
Year 4	0	0
Year 5	0	0
Prior	$ 32,000	$ 32,000
3
Financing Receivable, Credit Quality Indicator [Line Items]
Number of Loans \| loan	62	62
Total	$ 7,372,081	$ 6,129,541
Mortgage loans on real estate, commercial and consumer, percentage of portfolio	93.50%	93.80%
Year 1	$ 2,622,248	$ 469,586
Year 2	644,404	2,661,017
Year 3	2,307,948	1,398,479
Year 4	828,270	868,514
Year 5	389,264	88,710
Prior	$ 579,947	$ 643,235
4
Financing Receivable, Credit Quality Indicator [Line Items]
Number of Loans \| loan	1	0
Total	$ 81,980	$ 0
Mortgage loans on real estate, commercial and consumer, percentage of portfolio	1.00%	0.00%
Year 1	$ 0	$ 0
Year 2	0	0
Year 3	0	0
Year 4	0	0
Year 5	81,980	0
Prior	$ 0	$ 0
5
Financing Receivable, Credit Quality Indicator [Line Items]
Number of Loans \| loan	3	4
Total	$ 404,787	$ 373,538
Mortgage loans on real estate, commercial and consumer, percentage of portfolio	5.10%	5.70%
Year 1	$ 0	$ 0
Year 2	0	0
Year 3	0	0
Year 4	0	131,050
Year 5	177,483	115,419
Prior	$ 227,304	$ 127,069

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The reserve to cover probable credit losses related to specifically identified fixed maturity real estate loans as well as probable credit losses inherent in the remainder of that loan portfolio.

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Amount of financing receivable originated more than five years prior to current fiscal year.

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