Investment Securities Schedule of Amortized Cost and Fair Values of Investment Securities (Details) (USD $)	Dec. 31, 2013	Dec. 31, 2012
Statement [Line Items]
Held-to-maturity Securities	$ 0	$ 292,000
Held-to-maturity Securities, Fair Value		319,000
Available-for-sale Securities, Amortized Cost Basis	2,608,210,000	2,679,285,000
Available-for-sale Securities, Gross Unrealized Gain, Accumulated Investments	46,681,000	74,497,000
Available-for-sale Securities, Gross Unrealized Loss, Accumulated Investments	86,457,000	32,992,000
Available-for-sale Securities	2,568,434,000	2,720,790,000
Mortgage Backed Securities [Member]
Statement [Line Items]
Held-to-maturity Securities		292,000
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain		27,000
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss		0
Held-to-maturity Securities, Fair Value		319,000
Available-for-sale Securities, Amortized Cost Basis	949,328,000	847,790,000
Available-for-sale Securities, Gross Unrealized Gain, Accumulated Investments	13,881,000	31,831,000
Available-for-sale Securities, Gross Unrealized Loss, Accumulated Investments	17,497,000	0
Available-for-sale Securities	945,712,000	879,621,000
Equity Securities [Member]
Statement [Line Items]
Available-for-sale Securities, Amortized Cost Basis	33,922,000	45,530,000
Available-for-sale Securities, Gross Unrealized Gain, Accumulated Investments	12,355,000	5,016,000
Available-for-sale Securities, Gross Unrealized Loss, Accumulated Investments	76,000	918,000
Available-for-sale Securities	46,201,000	49,628,000
U.S. Government Securities [Member]
Statement [Line Items]
Available-for-sale Securities, Amortized Cost Basis	525,000	325,000
Available-for-sale Securities, Gross Unrealized Gain, Accumulated Investments	0	0
Available-for-sale Securities, Gross Unrealized Loss, Accumulated Investments	0	0
Available-for-sale Securities	525,000	325,000
U.S. Government-Sponsored Agency Securities [Member]
Statement [Line Items]
Available-for-sale Securities, Amortized Cost Basis	720,000	2,376,000
Available-for-sale Securities, Gross Unrealized Gain, Accumulated Investments	7,000	21,000
Available-for-sale Securities, Gross Unrealized Loss, Accumulated Investments	1,000	0
Available-for-sale Securities	726,000	2,397,000
State and Municipal Securities [Member]
Statement [Line Items]
Available-for-sale Securities, Amortized Cost Basis	281,810,000	301,842,000
Available-for-sale Securities, Gross Unrealized Gain, Accumulated Investments	6,483,000	13,763,000
Available-for-sale Securities, Gross Unrealized Loss, Accumulated Investments	3,444,000	86,000
Available-for-sale Securities	284,849,000	315,519,000
Corporate Debt Securities [Member]
Statement [Line Items]
Available-for-sale Securities, Amortized Cost Basis	100,468,000	112,162,000
Available-for-sale Securities, Gross Unrealized Gain, Accumulated Investments	5,685,000	7,858,000
Available-for-sale Securities, Gross Unrealized Loss, Accumulated Investments	7,404,000	7,178,000
Available-for-sale Securities	98,749,000	112,842,000
Collateralized Mortgage Obligations [Member]
Statement [Line Items]
Available-for-sale Securities, Amortized Cost Basis	1,069,138,000	1,195,234,000
Available-for-sale Securities, Gross Unrealized Gain, Accumulated Investments	8,036,000	16,008,000
Available-for-sale Securities, Gross Unrealized Loss, Accumulated Investments	44,776,000	123,000
Available-for-sale Securities	1,032,398,000	1,211,119,000
Auction Rate Securities [Member]
Statement [Line Items]
Available-for-sale Securities, Amortized Cost Basis	172,299,000	174,026,000
Available-for-sale Securities, Gross Unrealized Gain, Accumulated Investments	234,000	0
Available-for-sale Securities, Gross Unrealized Loss, Accumulated Investments	13,259,000	24,687,000
Available-for-sale Securities	$ 159,274,000	$ 149,339,000