Investment Securities (Schedule of Investment Securities Available for Sale) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	$ 1,123,399	$ 506,258
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	336,578	554,501
Amortized Cost	4,685,270	4,474,490
Gross Unrealized Gains	123,530	127,295
Gross Unrealized Losses	11,100	16,091
Investment securities available for sale, at fair value	4,797,700	4,585,694
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	1,459,977	1,060,759
U.S. Treasury securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	54,940	54,924
Gross Unrealized Gains	308	43
Gross Unrealized Losses	0	0
Investment securities available for sale, at fair value	55,248	54,967
U.S. Government agency and sponsored enterprise residential mortgage-backed securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	10,087	7,058
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	261,622	300,057
Amortized Cost	1,353,079	1,501,504
Gross Unrealized Gains	31,391	29,613
Gross Unrealized Losses	2,461	6,401
Investment securities available for sale, at fair value	1,382,009	1,524,716
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	271,709	307,115
U.S. Government agency and sponsored enterprise commercial mortgage-backed securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	241
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0
Amortized Cost	100,639	101,089
Gross Unrealized Gains	708	769
Gross Unrealized Losses	1	0
Investment securities available for sale, at fair value	101,346	101,858
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	241
Re-Remics
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		335
Amortized Cost	135,525	179,664
Gross Unrealized Gains	2,623	3,613
Gross Unrealized Losses	0	5
Investment securities available for sale, at fair value	138,148	183,272
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		335
Private label residential mortgage-backed securities and CMOs
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	240,416	60,076
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	12,131	14,653
Amortized Cost	679,743	350,300
Gross Unrealized Gains	50,744	54,222
Gross Unrealized Losses	2,963	543
Investment securities available for sale, at fair value	727,524	403,979
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	252,547	74,729
Private label commercial mortgage-backed securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	257,350	103,900
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	62,825	239,456
Amortized Cost	986,538	1,156,166
Gross Unrealized Gains	11,850	10,254
Gross Unrealized Losses	1,272	4,935
Investment securities available for sale, at fair value	997,116	1,161,485
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	320,175	343,356
Single family rental real estate-backed securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	470,999	233,012
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0	0
Amortized Cost	555,445	446,079
Gross Unrealized Gains	261	468
Gross Unrealized Losses	3,802	3,530
Investment securities available for sale, at fair value	551,904	443,017
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	470,999	233,012
Collateralized loan obligations
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	49,900	49,565
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0	0
Amortized Cost	309,602	174,767
Gross Unrealized Gains	1,104	0
Gross Unrealized Losses	100	435
Investment securities available for sale, at fair value	310,606	174,332
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	49,900	49,565
Non-mortgage asset-backed securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value		2,796
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		0
Amortized Cost	81,513	96,250
Gross Unrealized Gains	3,448	3,824
Gross Unrealized Losses	0	6
Investment securities available for sale, at fair value	84,961	100,068
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		2,796
Preferred stocks
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	75,895	96,294
Gross Unrealized Gains	8,587	9,148
Gross Unrealized Losses	0	0
Investment securities available for sale, at fair value	84,482	105,442
State and municipal obligations
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	67,720
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0
Amortized Cost	96,868	15,317
Gross Unrealized Gains	262	385
Gross Unrealized Losses	435	0
Investment securities available for sale, at fair value	96,695	15,702
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	67,720
Small Business Administration (SBA) securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	26,686	49,851
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0	0
Amortized Cost	251,700	298,424
Gross Unrealized Gains	7,726	10,540
Gross Unrealized Losses	66	236
Investment securities available for sale, at fair value	259,360	308,728
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	26,686	49,851
Other debt securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	3,783	3,712
Gross Unrealized Gains	4,518	4,416
Gross Unrealized Losses	0	0
Investment securities available for sale, at fair value	$ 8,301	$ 8,128