Loans and Allowance for Loan and Lease Losses (Schedule of Credit Exposure for New Loans Based on Original LTV and FICO Score) (Details) - New Loans - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Financing Receivable Recorded Investment [Line Items]
Non-covered loans, net of premiums, discounts and deferred fees and costs	$ 13,333,748	$ 11,277,489
1-4 single family residential
Financing Receivable Recorded Investment [Line Items]
Non-covered loans, net of premiums, discounts and deferred fees and costs	2,776,983	2,522,838
FICO, 720 or less | 1-4 single family residential
Financing Receivable Recorded Investment [Line Items]
Non-covered loans, net of premiums, discounts and deferred fees and costs	226,997	191,199
FICO, 721 to 740 | 1-4 single family residential
Financing Receivable Recorded Investment [Line Items]
Non-covered loans, net of premiums, discounts and deferred fees and costs	266,946	244,473
FICO, 741 to 760 | 1-4 single family residential
Financing Receivable Recorded Investment [Line Items]
Non-covered loans, net of premiums, discounts and deferred fees and costs	428,716	403,924
FICO, 761 or greater | 1-4 single family residential
Financing Receivable Recorded Investment [Line Items]
Non-covered loans, net of premiums, discounts and deferred fees and costs	1,854,324	1,683,242
60% or less | 1-4 single family residential
Financing Receivable Recorded Investment [Line Items]
Non-covered loans, net of premiums, discounts and deferred fees and costs	960,395	869,066
60% or less | FICO, 720 or less | 1-4 single family residential
Financing Receivable Recorded Investment [Line Items]
Non-covered loans, net of premiums, discounts and deferred fees and costs	78,553	64,590
60% or less | FICO, 721 to 740 | 1-4 single family residential
Financing Receivable Recorded Investment [Line Items]
Non-covered loans, net of premiums, discounts and deferred fees and costs	95,178	79,518
60% or less | FICO, 741 to 760 | 1-4 single family residential
Financing Receivable Recorded Investment [Line Items]
Non-covered loans, net of premiums, discounts and deferred fees and costs	137,282	128,115
60% or less | FICO, 761 or greater | 1-4 single family residential
Financing Receivable Recorded Investment [Line Items]
Non-covered loans, net of premiums, discounts and deferred fees and costs	649,382	596,843
60% - 70% | 1-4 single family residential
Financing Receivable Recorded Investment [Line Items]
Non-covered loans, net of premiums, discounts and deferred fees and costs	710,002	645,258
60% - 70% | FICO, 720 or less | 1-4 single family residential
Financing Receivable Recorded Investment [Line Items]
Non-covered loans, net of premiums, discounts and deferred fees and costs	66,897	55,075
60% - 70% | FICO, 721 to 740 | 1-4 single family residential
Financing Receivable Recorded Investment [Line Items]
Non-covered loans, net of premiums, discounts and deferred fees and costs	69,377	63,642
60% - 70% | FICO, 741 to 760 | 1-4 single family residential
Financing Receivable Recorded Investment [Line Items]
Non-covered loans, net of premiums, discounts and deferred fees and costs	102,870	102,054
60% - 70% | FICO, 761 or greater | 1-4 single family residential
Financing Receivable Recorded Investment [Line Items]
Non-covered loans, net of premiums, discounts and deferred fees and costs	470,858	424,487
70% - 80% | 1-4 single family residential
Financing Receivable Recorded Investment [Line Items]
Non-covered loans, net of premiums, discounts and deferred fees and costs	1,060,422	961,838
70% - 80% | FICO, 720 or less | 1-4 single family residential
Financing Receivable Recorded Investment [Line Items]
Non-covered loans, net of premiums, discounts and deferred fees and costs	53,843	43,316
70% - 80% | FICO, 721 to 740 | 1-4 single family residential
Financing Receivable Recorded Investment [Line Items]
Non-covered loans, net of premiums, discounts and deferred fees and costs	98,624	98,052
70% - 80% | FICO, 741 to 760 | 1-4 single family residential
Financing Receivable Recorded Investment [Line Items]
Non-covered loans, net of premiums, discounts and deferred fees and costs	185,232	170,305
70% - 80% | FICO, 761 or greater | 1-4 single family residential
Financing Receivable Recorded Investment [Line Items]
Non-covered loans, net of premiums, discounts and deferred fees and costs	722,723	650,165
More than 80% | 1-4 single family residential
Financing Receivable Recorded Investment [Line Items]
Non-covered loans, net of premiums, discounts and deferred fees and costs	46,164	46,676
More than 80% | FICO, 720 or less | 1-4 single family residential
Financing Receivable Recorded Investment [Line Items]
Non-covered loans, net of premiums, discounts and deferred fees and costs	27,704	28,218
More than 80% | FICO, 721 to 740 | 1-4 single family residential
Financing Receivable Recorded Investment [Line Items]
Non-covered loans, net of premiums, discounts and deferred fees and costs	3,767	3,261
More than 80% | FICO, 741 to 760 | 1-4 single family residential
Financing Receivable Recorded Investment [Line Items]
Non-covered loans, net of premiums, discounts and deferred fees and costs	3,332	3,450
More than 80% | FICO, 761 or greater | 1-4 single family residential
Financing Receivable Recorded Investment [Line Items]
Non-covered loans, net of premiums, discounts and deferred fees and costs	$ 11,361	$ 11,747