Commitments - Extensions of Credit (Details) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Extended lines of credit
Commitments, guarantees:
Unused amounts in lines of credit to third-party entities and commitments for future financing to clients	$ 5,931	$ 5,477
Financing for client purchase agreements
Commitments, guarantees:
Unused amounts in lines of credit to third-party entities and commitments for future financing to clients	$ 2,252	$ 2,097

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