Fair Value Measurements - Carrying Amounts and Estimated Fair Values of Financial Instruments Not Measured at Fair Value (Details) - USD ($) $ in Millions	Dec. 31, 2021		Dec. 31, 2020
Carrying Amount
Assets:
Cash and cash equivalents	$ 1,228		$ 1,275
Deposits with banks	58		46
Notes receivable, net	32		30
Secured financings receivable	565		748
Loans eligible for repurchase	47
Liabilities:
Secured financings payable	529	[1]	516
Liability for loans eligible for repurchase	47
Notes and contracts payable	1,648		1,011
Estimated Fair Value
Assets:
Cash and cash equivalents	1,228		1,275
Deposits with banks	58		46
Notes receivable, net	32		30
Secured financings receivable	565		748
Loans eligible for repurchase	47
Liabilities:
Secured financings payable	529	[1]	516
Liability for loans eligible for repurchase	47
Notes and contracts payable	1,724		1,131
Estimated Fair Value | Level 1
Assets:
Cash and cash equivalents	1,228		1,275
Deposits with banks	13		6
Notes receivable, net	0		0
Secured financings receivable	0		0
Loans eligible for repurchase	0
Liabilities:
Secured financings payable	0	[1]	0
Liability for loans eligible for repurchase	0
Notes and contracts payable	0		0
Estimated Fair Value | Level 2
Assets:
Cash and cash equivalents	0		0
Deposits with banks	45		40
Notes receivable, net	0		0
Secured financings receivable	565		748
Loans eligible for repurchase	47
Liabilities:
Secured financings payable	529	[1]	516
Liability for loans eligible for repurchase	47
Notes and contracts payable	1,720		1,125
Estimated Fair Value | Level 3
Assets:
Cash and cash equivalents	0		0
Deposits with banks	0		0
Notes receivable, net	32		30
Secured financings receivable	0		0
Loans eligible for repurchase	0
Liabilities:
Secured financings payable	0	[1]	0
Liability for loans eligible for repurchase	0
Notes and contracts payable	$ 4		$ 6

[1] Excludes servicing related liabilities, which are measured at fair value on a recurring basis.