Segment Information - Additional Information (Detail) $ in Millions	3 Months Ended
Mar. 31, 2015 USD ($)
Residential Mortgage Banking [Member]
Segment Reporting Information [Line Items]
Decrease in revenues	$ 6
Decrease in net income	3
Commercial Real Estate [Member]
Segment Reporting Information [Line Items]
Increase in revenues	6
Increase in net income	$ 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.

No definition available.

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