Commitments and Contingencies (Details) - Commitments $ in Billions	Sep. 30, 2017 USD ($) loan
Operating leases
Number of loans with future funding commitments \| loan	51
Value of loans with future funding commitments	$ 1.5
Value of loans with future funding commitments expected to fund	$ 1.3

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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