Fair Value Measurements - Fair Value Option on Consolidated VIEs and Equity Method Investments (Details) - Real Estate Ventures - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Fair Value Option, Quantitative Disclosures
Fair value of assets for which fair value option was elected	$ 37.8		$ 28.5
Pre-tax gain (loss) due to change in fair value of assets and liabilities for which the fair value option was elected	$ 9.3	$ (0.1)

For each line item in the statement of financial position, the amounts of gains and losses from fair value changes included in earnings.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 30
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=75031198&loc=d3e14172-108612

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