Fair Value Measurements - Rollforward of Financial Instruments Classified in Level Three of Valuation Hierarchy (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Transfer to / (from) level 3	$ 0	$ 0
Available-for-sale capital securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Beginning Balance		18,569
Total Realized/Unrealized Gains/(Losses) Recorded in Comprehensive (Loss) Income		(2,413)
Settlements		0
Transfer to / (from) level 3		0
Fair Value, Ending Balance		20,982
Change in Unrealized Gains and (Losses) Related to Instruments Held		2,413
Mortgage servicing rights
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Beginning Balance	241,018	144,520
Total Realized/Unrealized Gains/(Losses) Recorded in (Loss) Income	27,417	(10,187)
Total Realized/Unrealized Gains/(Losses) Recorded in Comprehensive (Loss) Income	0
Issuances	23,620	73,398
Settlements	0	0
Transfer to / (from) level 3	0	0
Fair Value, Ending Balance	237,221	228,105
Change in Unrealized Gains and (Losses) Related to Instruments Held	13,091	54,437
Interest rate lock commitments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Beginning Balance	258	21,446
Total Realized/Unrealized Gains/(Losses) Recorded in (Loss) Income	(1,922)	15,256
Total Realized/Unrealized Gains/(Losses) Recorded in Comprehensive (Loss) Income	0
Settlements	0	0
Transfer to / (from) level 3	0	0
Fair Value, Ending Balance	2,180	6,190
Change in Unrealized Gains and (Losses) Related to Instruments Held	$ 2,180	$ 6,190