Loans and Interest Receivable, Net - Loans and Interest Receivables by FICO Score (Details) - Consumer Receivables - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment [Line Items]
Consumer loans and interest receivable	$ 5,669	$ 4,996
Greater than 760
Financing Receivable, Recorded Investment [Line Items]
Consumer loans and interest receivable	710	665
680 - 759
Financing Receivable, Recorded Investment [Line Items]
Consumer loans and interest receivable	2,157	1,938
600 - 679
Financing Receivable, Recorded Investment [Line Items]
Consumer loans and interest receivable	2,137	1,840
Less Than 599
Financing Receivable, Recorded Investment [Line Items]
Consumer loans and interest receivable	$ 665	$ 553