Derivative Financial Instruments - Schedule of Notional or Contractual Amounts and Fair Values of Derivative Instruments (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Derivative [Line Items]
Notional Amount
Derivative Assets, Fair Value	229,383	949
Derivative Liabilities, Fair Value	58,606	1,102
Derivative Assets, Fair Value, Cash collateral	31
Collateral payable on derivative instruments	124,759
Interest Rate Lock Commitments [Member]
Derivative [Line Items]
Notional Amount	4,190,048	35,266
Derivative Assets, Fair Value	61,680	949
Derivative Liabilities, Fair Value	19,327
Forward Sales Commitments [Member]
Derivative [Line Items]
Notional Amount	7,326,249	42,078
Derivative Assets, Fair Value	163,199
Derivative Liabilities, Fair Value	10,113	1,102
Loan Purchase Commitments [Member]
Derivative [Line Items]
Notional Amount	2,172,000
Derivative Assets, Fair Value	4,504
Derivative Liabilities, Fair Value	$ 29,166