Loans and Allowance for Loan and Lease Losses (Schedule of Financing Receivables Past Due) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Financing Receivable Investment Past Due [Line Items]
Loans net of premiums, discounts and deferred fees and costs	$ 12,414,769	$ 9,053,609
Covered loans net of premiums, discounts and deferred fees and costs	1,043,864	1,483,888
1-4 single family residential
Financing Receivable Investment Past Due [Line Items]
Loans net of premiums, discounts and deferred fees and costs	3,444,525	2,944,462
Covered loans net of premiums, discounts and deferred fees and costs	921,687	1,116,682
Consumer
Financing Receivable Investment Past Due [Line Items]
Loans net of premiums, discounts and deferred fees and costs	26,260	221,720
New Loans
Financing Receivable Investment Past Due [Line Items]
Loans, Current	11,259,078	7,541,167
Loans, 30-59 Days Past Due	13,360	4,366
Loans, 60-89 Days Past Due	583	460
Loans, 90 Days or More Past Due or in Foreclosure	4,468	8,868
Non-covered loans, net of premiums, discounts and deferred fees and costs	11,277,489	7,554,861
New Loans | 1-4 single family residential
Financing Receivable Investment Past Due [Line Items]
Loans, Current	2,518,357	1,824,084
Loans, 30-59 Days Past Due	4,432	2,990
Loans, 60-89 Days Past Due	0	109
Loans, 90 Days or More Past Due or in Foreclosure	49	597
Non-covered loans, net of premiums, discounts and deferred fees and costs	2,522,838	1,827,780
New Loans | Home equity loans and lines of credit
Financing Receivable Investment Past Due [Line Items]
Loans, Current	1,827	1,535
Loans, 30-59 Days Past Due	0	0
Loans, 60-89 Days Past Due	0	0
Loans, 90 Days or More Past Due or in Foreclosure	0	0
Non-covered loans, net of premiums, discounts and deferred fees and costs	1,827	1,535
New Loans | Multi-family
Financing Receivable Investment Past Due [Line Items]
Loans, Current	1,929,546	1,099,153
Loans, 30-59 Days Past Due	1,186	0
Loans, 60-89 Days Past Due	0	0
Loans, 90 Days or More Past Due or in Foreclosure	0	0
Non-covered loans, net of premiums, discounts and deferred fees and costs	1,930,732	1,099,153
New Loans | Commercial real estate, Owner occupied
Financing Receivable Investment Past Due [Line Items]
Loans, Current	1,008,576	710,938
Loans, 30-59 Days Past Due	836	0
Loans, 60-89 Days Past Due	0	0
Loans, 90 Days or More Past Due or in Foreclosure	379	596
Non-covered loans, net of premiums, discounts and deferred fees and costs	1,009,791	711,534
New Loans | Commercial real estate, Non-owner occupied
Financing Receivable Investment Past Due [Line Items]
Loans, Current	1,752,079	947,652
Loans, 30-59 Days Past Due	0	0
Loans, 60-89 Days Past Due	0	0
Loans, 90 Days or More Past Due or in Foreclosure	0	0
Non-covered loans, net of premiums, discounts and deferred fees and costs	1,752,079	947,652
New Loans | Construction and land
Financing Receivable Investment Past Due [Line Items]
Loans, Current	167,138	137,757
Loans, 30-59 Days Past Due	0	0
Loans, 60-89 Days Past Due	0	0
Loans, 90 Days or More Past Due or in Foreclosure	0	0
Non-covered loans, net of premiums, discounts and deferred fees and costs	167,138	137,757
New Loans | Commercial and industrial
Financing Receivable Investment Past Due [Line Items]
Loans, Current	2,396,549	1,644,292
Loans, 30-59 Days Past Due	1,696	494
Loans, 60-89 Days Past Due	327	165
Loans, 90 Days or More Past Due or in Foreclosure	2,007	7,644
Non-covered loans, net of premiums, discounts and deferred fees and costs	2,400,579	1,652,595
New Loans | Commercial finance subsidiaries
Financing Receivable Investment Past Due [Line Items]
Loans, Current	1,458,890	956,673
Loans, 30-59 Days Past Due	5,208	116
Loans, 60-89 Days Past Due	246	25
Loans, 90 Days or More Past Due or in Foreclosure	1,915	0
Non-covered loans, net of premiums, discounts and deferred fees and costs	1,466,259	956,814
New Loans | Consumer
Financing Receivable Investment Past Due [Line Items]
Loans, Current	26,116	219,083
Loans, 30-59 Days Past Due	2	766
Loans, 60-89 Days Past Due	10	161
Loans, 90 Days or More Past Due or in Foreclosure	118	31
Non-covered loans, net of premiums, discounts and deferred fees and costs	26,246	220,041
Non-ACI loans
Financing Receivable Investment Past Due [Line Items]
Loans, Current	139,386	177,433
Loans, 30-59 Days Past Due	2,341	5,546
Loans, 60-89 Days Past Due	1,109	853
Loans, 90 Days or More Past Due or in Foreclosure	3,849	8,809
Covered loans net of premiums, discounts and deferred fees and costs	146,685	192,641
Non-ACI loans | 1-4 single family residential
Financing Receivable Investment Past Due [Line Items]
Loans, Current	45,959	56,248
Loans, 30-59 Days Past Due	602	3,129
Loans, 60-89 Days Past Due	563	293
Loans, 90 Days or More Past Due or in Foreclosure	41	0
Covered loans net of premiums, discounts and deferred fees and costs	47,165	59,670
Non-ACI loans | Home equity loans and lines of credit
Financing Receivable Investment Past Due [Line Items]
Loans, Current	93,427	116,036
Loans, 30-59 Days Past Due	1,739	2,417
Loans, 60-89 Days Past Due	546	556
Loans, 90 Days or More Past Due or in Foreclosure	3,808	6,559
Covered loans net of premiums, discounts and deferred fees and costs	99,520	125,568
Non-ACI loans | Multi-family
Financing Receivable Investment Past Due [Line Items]
Covered loans net of premiums, discounts and deferred fees and costs		0
Non-ACI loans | Commercial real estate, Owner occupied
Financing Receivable Investment Past Due [Line Items]
Loans, Current	0	687
Loans, 30-59 Days Past Due	0	0
Loans, 60-89 Days Past Due	0	0
Loans, 90 Days or More Past Due or in Foreclosure	0	0
Covered loans net of premiums, discounts and deferred fees and costs		687
Non-covered loans, net of premiums, discounts and deferred fees and costs	0
Non-ACI loans | Commercial real estate, Non-owner occupied
Financing Receivable Investment Past Due [Line Items]
Loans, Current	0	52
Loans, 30-59 Days Past Due	0	0
Loans, 60-89 Days Past Due	0	0
Loans, 90 Days or More Past Due or in Foreclosure	0	0
Covered loans net of premiums, discounts and deferred fees and costs		52
Non-covered loans, net of premiums, discounts and deferred fees and costs	0
Non-ACI loans | Construction and land
Financing Receivable Investment Past Due [Line Items]
Loans, Current	0	688
Loans, 30-59 Days Past Due	0	0
Loans, 60-89 Days Past Due	0	0
Loans, 90 Days or More Past Due or in Foreclosure	0	0
Covered loans net of premiums, discounts and deferred fees and costs		688
Non-covered loans, net of premiums, discounts and deferred fees and costs	0
Non-ACI loans | Commercial and industrial
Financing Receivable Investment Past Due [Line Items]
Loans, Current	0	3,722
Loans, 30-59 Days Past Due	0	0
Loans, 60-89 Days Past Due	0	4
Loans, 90 Days or More Past Due or in Foreclosure	0	2,250
Covered loans net of premiums, discounts and deferred fees and costs		5,976
Non-covered loans, net of premiums, discounts and deferred fees and costs	0
Non-ACI loans | Commercial finance subsidiaries
Financing Receivable Investment Past Due [Line Items]
Covered loans net of premiums, discounts and deferred fees and costs		0
ACI loans
Financing Receivable Investment Past Due [Line Items]
Loans, Current	943,253	1,178,933
Loans, 30-59 Days Past Due	19,033	37,715
Loans, 60-89 Days Past Due	4,814	10,809
Loans, 90 Days or More Past Due or in Foreclosure	23,495	78,650
Loans net of premiums, discounts and deferred fees and costs	990,595	1,306,107
Covered loans net of premiums, discounts and deferred fees and costs		1,306,107
ACI loans | 1-4 single family residential
Financing Receivable Investment Past Due [Line Items]
Loans, Current	829,412	957,791
Loans, 30-59 Days Past Due	18,463	33,067
Loans, 60-89 Days Past Due	4,689	10,279
Loans, 90 Days or More Past Due or in Foreclosure	21,958	55,875
Covered loans net of premiums, discounts and deferred fees and costs	874,522	1,057,012
ACI loans | Home equity loans and lines of credit
Financing Receivable Investment Past Due [Line Items]
Loans, Current	20,474	33,967
Loans, 30-59 Days Past Due	558	1,150
Loans, 60-89 Days Past Due	125	329
Loans, 90 Days or More Past Due or in Foreclosure	1,500	4,156
Covered loans net of premiums, discounts and deferred fees and costs	22,657	39,602
ACI loans | Multi-family
Financing Receivable Investment Past Due [Line Items]
Loans, Current	24,964	38,877
Loans, 30-59 Days Past Due	0	0
Loans, 60-89 Days Past Due	0	0
Loans, 90 Days or More Past Due or in Foreclosure	0	2,570
Covered loans net of premiums, discounts and deferred fees and costs		41,447
Non-covered loans, net of premiums, discounts and deferred fees and costs	24,964
ACI loans | Commercial real estate, Owner occupied
Financing Receivable Investment Past Due [Line Items]
Loans, Current	34,440	54,501
Loans, 30-59 Days Past Due	0	253
Loans, 60-89 Days Past Due	0	0
Loans, 90 Days or More Past Due or in Foreclosure	0	425
Covered loans net of premiums, discounts and deferred fees and costs		55,179
Non-covered loans, net of premiums, discounts and deferred fees and costs	34,440
ACI loans | Commercial real estate, Non-owner occupied
Financing Receivable Investment Past Due [Line Items]
Loans, Current	30,746	81,754
Loans, 30-59 Days Past Due	9	3,245
Loans, 60-89 Days Past Due	0	0
Loans, 90 Days or More Past Due or in Foreclosure	7	9,539
Covered loans net of premiums, discounts and deferred fees and costs		94,538
Non-covered loans, net of premiums, discounts and deferred fees and costs	30,762
ACI loans | Construction and land
Financing Receivable Investment Past Due [Line Items]
Loans, Current	2,007	7,373
Loans, 30-59 Days Past Due	0	0
Loans, 60-89 Days Past Due	0	0
Loans, 90 Days or More Past Due or in Foreclosure	0	3,227
Covered loans net of premiums, discounts and deferred fees and costs		10,600
Non-covered loans, net of premiums, discounts and deferred fees and costs	2,007
ACI loans | Commercial and industrial
Financing Receivable Investment Past Due [Line Items]
Loans, Current	1,196	3,193
Loans, 30-59 Days Past Due	3	0
Loans, 60-89 Days Past Due	0	0
Loans, 90 Days or More Past Due or in Foreclosure	30	2,857
Covered loans net of premiums, discounts and deferred fees and costs		6,050
Non-covered loans, net of premiums, discounts and deferred fees and costs	1,229
ACI loans | Commercial finance subsidiaries
Financing Receivable Investment Past Due [Line Items]
Covered loans net of premiums, discounts and deferred fees and costs		0
Non-covered loans, net of premiums, discounts and deferred fees and costs	0
ACI loans | Consumer
Financing Receivable Investment Past Due [Line Items]
Loans, Current	14	1,477
Loans, 30-59 Days Past Due	0	0
Loans, 60-89 Days Past Due	0	201
Loans, 90 Days or More Past Due or in Foreclosure	0	1
Loans net of premiums, discounts and deferred fees and costs	14	1,679
Covered loans net of premiums, discounts and deferred fees and costs		1,679
Non-covered loans, net of premiums, discounts and deferred fees and costs	$ 14