Fair Values Of Assets And Liabilities (Narrative) (Detail)	6 Months Ended	12 Months Ended
	Jun. 30, 2017 USD ($) $ / Loan	Dec. 31, 2016 USD ($)	Jun. 30, 2016 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-investment	$ 30,173,000		$ 16,294,000
Derivative assets	49,703,000	$ 56,394,000	101,052,000
Mortgage loans held-for-sale	382,837,000	418,374,000	554,256,000
Impaired loans—collateral based	$ 79,318,000	90,516,000	95,976,000
Other real estate owned, including covered other real estate owned
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Appraisal adjustment - cost of sale	10.00%
Estimate of Fair Value Measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
MSRs	$ 27,307,000	19,103,000	13,382,000
Remaining contractual principal balance outstanding, mortgage loans held-for-sale	368,800,000	414,400,000	529,000,000
Mortgage loans held-for-sale	382,837,000	418,374,000	554,256,000
Impaired loans—collateral based	57,300,000
Portion at Other than Fair Value Measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans—collateral based	$ 22,000,000
Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Pull-through rate	40.00%
Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Pull-through rate	100.00%
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-investment	$ 30,173,000	22,137,000	16,294,000
MSRs	27,307,000	19,103,000	13,382,000
Derivative assets	49,703,000	56,394,000	101,052,000
Mortgage loans held-for-sale	382,837,000	418,374,000	554,256,000
Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans—collateral based	57,259,000
Other real estate owned, including covered other real estate owned	42,617,000
Level 3 | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-investment	30,173,000	22,137,000	0
MSRs	27,307,000	19,103,000	13,382,000
Derivative assets	1,047,000	2,291,000	9,731,000
Mortgage loans held-for-sale	$ 0	0	0
Level 3 | Fair Value, Measurements, Recurring | Loans held-for-investment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Constant prepayment rate (CPR)	9.42%
Level 3 | Fair Value, Measurements, Recurring | Minimum | Loans held-for-investment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rate input	3.00%
Credit loss rate	0.00%
Level 3 | Fair Value, Measurements, Recurring | Minimum | Mortgage Servicing Rights
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rate input	9.00%
Constant prepayment rate (CPR)	0.00%
Level 3 | Fair Value, Measurements, Recurring | Maximum | Loans held-for-investment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rate input	4.00%
Credit loss rate	3.00%
Level 3 | Fair Value, Measurements, Recurring | Maximum | Mortgage Servicing Rights
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rate input	16.00%
Constant prepayment rate (CPR)	34.00%
Level 3 | Fair Value, Measurements, Recurring | Weighted Average | Loans held-for-investment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rate input	3.70%
Credit loss rate	0.89%
Level 3 | Fair Value, Measurements, Recurring | Weighted Average | Mortgage Servicing Rights
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rate input	9.81%
Constant prepayment rate (CPR)	9.64%
Range of Inputs (in dollars per loan) | $ / Loan	65
Weighted Average of Inputs (in dollars per loan) | $ / Loan	422
Level 3 | Fair Value, Measurements, Recurring | Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gain on transfer		2,400,000
Level 3 | Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans—collateral based	$ 57,259,000
Other real estate owned, including covered other real estate owned	42,617,000
Non-performing
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage loans held-for-sale	$ 0	$ 0	$ 0