Investment Securities (Schedule of Investment Securities Portfolio Continuous Unrealized Loss Position) (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale, continuous unrealized losses existing for less than 12 months, Fair value	$ 1,257,582	$ 170,847
Available-for-sale, continuous unrealized losses existing for less than 12 months, Unrealized losses	(22,293)	(540)
Available-for-sale, continuous unrealized losses existing for greater than 12 months, Fair value	185,788	921,875
Available-for-sale, continuous unrealized losses existing for greater than 12 months, Unrealized losses	(7,377)	(37,440)
Available-for-sale, continuous unrealized loss position, Fair value	1,443,370	1,092,722
Available-for-sale, continuous unrealized loss position, Unrealized losses	(29,670)	(37,980)
Held-to-maturity securities, continuous unrealized loss position, less than 12 months, Fair value	502,733	0
Held-to-maturity securities, continuous unrealized loss position, less than 12 months, Unrealized loss	(4,505)	0
Held-to-maturity securities, continuous unrealized loss position, 12 months or longer, Fair value	264,710	0
Held-to-maturity securities, continuous unrealized loss position, 12 months or longer, Unrealized loss	(3,081)	0
Held-to-maturity securities, continuous unrealized loss position, Fair value	767,443	0
Held-to-maturity securities, continuous unrealized loss position, Unrealized loss	(7,586)	0
U.S. Treasury
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale, continuous unrealized losses existing for less than 12 months, Fair value	306,729	97,395
Available-for-sale, continuous unrealized losses existing for less than 12 months, Unrealized losses	(5,553)	(31)
Available-for-sale, continuous unrealized losses existing for greater than 12 months, Fair value	0	193,187
Available-for-sale, continuous unrealized losses existing for greater than 12 months, Unrealized losses	0	(6,961)
Available-for-sale, continuous unrealized loss position, Fair value	306,729	290,582
Available-for-sale, continuous unrealized loss position, Unrealized losses	(5,553)	(6,992)
Held-to-maturity securities, continuous unrealized loss position, less than 12 months, Fair value	450,800	0
Held-to-maturity securities, continuous unrealized loss position, less than 12 months, Unrealized loss	(4,223)	0
Held-to-maturity securities, continuous unrealized loss position, 12 months or longer, Fair value	235,518	0
Held-to-maturity securities, continuous unrealized loss position, 12 months or longer, Unrealized loss	(2,921)	0
Held-to-maturity securities, continuous unrealized loss position, Fair value	686,318	0
Held-to-maturity securities, continuous unrealized loss position, Unrealized loss	(7,144)	0
US Government agencies
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale, continuous unrealized losses existing for less than 12 months, Fair value	56,193	13,164
Available-for-sale, continuous unrealized losses existing for less than 12 months, Unrealized losses	(192)	(120)
Available-for-sale, continuous unrealized losses existing for greater than 12 months, Fair value	8,434	459,035
Available-for-sale, continuous unrealized losses existing for greater than 12 months, Unrealized losses	(83)	(21,783)
Available-for-sale, continuous unrealized loss position, Fair value	64,627	472,199
Available-for-sale, continuous unrealized loss position, Unrealized losses	(275)	(21,903)
Municipal
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale, continuous unrealized losses existing for less than 12 months, Fair value	24,673	40,904
Available-for-sale, continuous unrealized losses existing for less than 12 months, Unrealized losses	(261)	(315)
Available-for-sale, continuous unrealized losses existing for greater than 12 months, Fair value	3,680	45,438
Available-for-sale, continuous unrealized losses existing for greater than 12 months, Unrealized losses	(95)	(1,425)
Available-for-sale, continuous unrealized loss position, Fair value	28,353	86,342
Available-for-sale, continuous unrealized loss position, Unrealized losses	(356)	(1,740)
Held-to-maturity securities, continuous unrealized loss position, less than 12 months, Fair value	51,933	0
Held-to-maturity securities, continuous unrealized loss position, less than 12 months, Unrealized loss	(282)	0
Held-to-maturity securities, continuous unrealized loss position, 12 months or longer, Fair value	29,192	0
Held-to-maturity securities, continuous unrealized loss position, 12 months or longer, Unrealized loss	(160)	0
Held-to-maturity securities, continuous unrealized loss position, Fair value	81,125	0
Held-to-maturity securities, continuous unrealized loss position, Unrealized loss	(442)	0
Corporate notes, financial issuers
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale, continuous unrealized losses existing for less than 12 months, Fair value	16,225	1,311
Available-for-sale, continuous unrealized losses existing for less than 12 months, Unrealized losses	(266)	(1)
Available-for-sale, continuous unrealized losses existing for greater than 12 months, Fair value	34,744	57,624
Available-for-sale, continuous unrealized losses existing for greater than 12 months, Unrealized losses	(1,215)	(1,556)
Available-for-sale, continuous unrealized loss position, Fair value	50,969	58,935
Available-for-sale, continuous unrealized loss position, Unrealized losses	(1,481)	(1,557)
Corporate notes, other
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale, continuous unrealized losses existing for less than 12 months, Fair value	998	0
Available-for-sale, continuous unrealized losses existing for less than 12 months, Unrealized losses	(2)	0
Available-for-sale, continuous unrealized losses existing for greater than 12 months, Fair value	0	0
Available-for-sale, continuous unrealized losses existing for greater than 12 months, Unrealized losses	0	0
Available-for-sale, continuous unrealized loss position, Fair value	998	0
Available-for-sale, continuous unrealized loss position, Unrealized losses	(2)	0
Mortgage-backed securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale, continuous unrealized losses existing for less than 12 months, Fair value	835,086	4,875
Available-for-sale, continuous unrealized losses existing for less than 12 months, Unrealized losses	(15,753)	(60)
Available-for-sale, continuous unrealized losses existing for greater than 12 months, Fair value	121,249	142,301
Available-for-sale, continuous unrealized losses existing for greater than 12 months, Unrealized losses	(5,251)	(4,868)
Available-for-sale, continuous unrealized loss position, Fair value	956,335	147,176
Available-for-sale, continuous unrealized loss position, Unrealized losses	(21,004)	(4,928)
Mortgage-backed, collateralized mortgage obligations
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale, continuous unrealized losses existing for less than 12 months, Fair value	12,782	13,198
Available-for-sale, continuous unrealized losses existing for less than 12 months, Unrealized losses	(189)	(13)
Available-for-sale, continuous unrealized losses existing for greater than 12 months, Fair value	9,196	14,828
Available-for-sale, continuous unrealized losses existing for greater than 12 months, Unrealized losses	(317)	(522)
Available-for-sale, continuous unrealized loss position, Fair value	21,978	28,026
Available-for-sale, continuous unrealized loss position, Unrealized losses	(506)	(535)
Equity securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale, continuous unrealized losses existing for less than 12 months, Fair value	4,896	0
Available-for-sale, continuous unrealized losses existing for less than 12 months, Unrealized losses	(77)	0
Available-for-sale, continuous unrealized losses existing for greater than 12 months, Fair value	8,485	9,462
Available-for-sale, continuous unrealized losses existing for greater than 12 months, Unrealized losses	(416)	(325)
Available-for-sale, continuous unrealized loss position, Fair value	13,381	9,462
Available-for-sale, continuous unrealized loss position, Unrealized losses	$ (493)	$ (325)