Fair Value - Schedule of Net Gains on Sales of Loans (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Components of Net Gains on Sales of Loans [Line Items]
Realized gains on sales of loans	$ 82,683	$ 79,999	$ 108,768	$ 160,079
Change in unrealized gains on loans held for sale	(6,046)	2,548	13,612	12,839
Capitalized servicing rights	19,006	46,279	51,390	98,537
Provision for repurchases	(2,003)	(3,724)	(3,798)	(8,437)
Interest income	9,222	9,540	20,425	19,933
Other	(305)	0	(294)	0
Net gains on sales of loans	70,545	100,176	144,901	184,653
Interest Rate Lock Commitments
Components of Net Gains on Sales of Loans [Line Items]
Gains (losses) on derivative instruments	(15,052)	11,395	(19,578)	25,312
Forward Sales Commitments
Components of Net Gains on Sales of Loans [Line Items]
Gains (losses) on derivative instruments	(2,858)	(43,384)	(23,406)	(110,337)
MBS Purchase Commitments
Components of Net Gains on Sales of Loans [Line Items]
Gains (losses) on derivative instruments	$ (14,102)	$ (2,477)	$ (2,218)	$ (13,273)