Investments - Schedule of Other Long-Term Investments (Detail) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2020	Dec. 31, 2019
Long-Term Investment [Line Items]
Other long-term investments	$ 377,239	$ 326,347
Capital called from investment funds	$ 25,000
Investment funds \| Minimum
Long-Term Investment [Line Items]
Investment funds ownership percentage	1.00%
Investment funds \| Maximum
Long-Term Investment [Line Items]
Investment funds ownership percentage	20.00%
Commercial mortgage participations
Long-Term Investment [Line Items]
Other long-term investments	$ 161,841	137,692
Other
Long-Term Investment [Line Items]
Other long-term investments	3,607	2,804
Partnership Interest - Fair Value Option \| Investment funds
Long-Term Investment [Line Items]
Other long-term investments	$ 211,791	$ 185,851

Long-Term Investment

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Amount of long-term investments classified as other.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
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The cash outflow for securities or other assets acquired, which qualify for treatment as an investing activity and are to be liquidated, if necessary, beyond the current operating cycle. Includes cash flows from securities classified as trading securities that were acquired for reasons other than sale in the long-term.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3213-108585

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Percentage of the Variable Interest Entity's (VIE) voting interest owned by (or beneficial interest in) the reporting entity (directly or indirectly).

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 5A
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