Rollforward of Financial Instruments Classified in Level Three of Valuation Hierarchy (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Mortgage servicing rights
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Beginning Balance	$ 227,297
Total Realized/Unrealized Gains/(Losses) Recorded in (Loss) Income	(35,092)
Total Realized/Unrealized Gains/(Losses) Recorded in Comprehensive (Loss) Income	0
Issuances	40,217
Settlements	0
Transfers to/(from) level 3	0
Fair Value, Ending Balance	232,422
Change in Unrealized Gains and (Losses) Related to Instruments Held	8,941
Interest rate lock commitments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Beginning Balance	4,397	$ 258
Total Realized/Unrealized Gains/(Losses) Recorded in (Loss) Income	847	1,922
Total Realized/Unrealized Gains/(Losses) Recorded in Comprehensive (Loss) Income	0	0
Settlements	0	0
Transfers to/(from) level 3	0
Fair Value, Ending Balance	5,244	2,180
Change in Unrealized Gains and (Losses) Related to Instruments Held	$ 5,244	2,180
Available-for-sale capital securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Beginning Balance		241,018
Total Realized/Unrealized Gains/(Losses) Recorded in (Loss) Income		(27,417)
Total Realized/Unrealized Gains/(Losses) Recorded in Comprehensive (Loss) Income		0
Issuances		23,620
Settlements		0
Fair Value, Ending Balance		237,221
Change in Unrealized Gains and (Losses) Related to Instruments Held		$ 13,091