Investment Securities, Available-for-sale Securities, Gross Unrealized Loss Position (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Available for sale securities unrealized loss position - Fair Value [Abstract]
Less than 12 months - Fair Value	$ 538,070	$ 778,568
12 months or more - Fair Value	147,309	54,835
Total - Fair Value	685,379	833,403
Available for sale securities unrealized loss position - Gross Unrealized Loss [Abstract]
Less than 12 months - Gross Unrealized Loss	15,635	28,184
12 months or more - Gross Unrealized Loss	7,571	2,350
Total - Gross Unrealized Loss	23,206	30,534
U. S. government sponsored enterprises [Member]
Available for sale securities unrealized loss position - Fair Value [Abstract]
Less than 12 months - Fair Value	86,885	198,023
12 months or more - Fair Value	0	0
Total - Fair Value	86,885	198,023
Available for sale securities unrealized loss position - Gross Unrealized Loss [Abstract]
Less than 12 months - Gross Unrealized Loss	1,136	1,724
12 months or more - Gross Unrealized Loss	0	0
Total - Gross Unrealized Loss	1,136	1,724
Mortgage-backed securities and collateralized mortgage obligations-residential [Member]
Available for sale securities unrealized loss position - Fair Value [Abstract]
Less than 12 months - Fair Value	400,364	466,056
12 months or more - Fair Value	84,672	54,835
Total - Fair Value	485,036	520,891
Available for sale securities unrealized loss position - Gross Unrealized Loss [Abstract]
Less than 12 months - Gross Unrealized Loss	11,436	17,698
12 months or more - Gross Unrealized Loss	2,811	2,350
Total - Gross Unrealized Loss	14,247	20,048
Corporate bonds [Member]
Available for sale securities unrealized loss position - Fair Value [Abstract]
Less than 12 months - Fair Value	501	902
12 months or more - Fair Value	0	0
Total - Fair Value	501	902
Available for sale securities unrealized loss position - Gross Unrealized Loss [Abstract]
Less than 12 months - Gross Unrealized Loss	2	1
12 months or more - Gross Unrealized Loss	0	0
Total - Gross Unrealized Loss	2	1
Small Business Administration-guaranteed participation securities [Member]
Available for sale securities unrealized loss position - Fair Value [Abstract]
Less than 12 months - Fair Value	39,184	103,029
12 months or more - Fair Value	62,637	0
Total - Fair Value	101,821	103,029
Available for sale securities unrealized loss position - Gross Unrealized Loss [Abstract]
Less than 12 months - Gross Unrealized Loss	2,699	8,354
12 months or more - Gross Unrealized Loss	4,760	0
Total - Gross Unrealized Loss	7,459	8,354
Mortgage-backed securities and collateralized mortgage obligations-Commercial [Member]
Available for sale securities unrealized loss position - Fair Value [Abstract]
Less than 12 months - Fair Value	10,543	10,558
12 months or more - Fair Value	0	0
Total - Fair Value	10,543	10,558
Available for sale securities unrealized loss position - Gross Unrealized Loss [Abstract]
Less than 12 months - Gross Unrealized Loss	355	407
12 months or more - Gross Unrealized Loss	0	0
Total - Gross Unrealized Loss	355	407
Other [Member]
Available for sale securities unrealized loss position - Fair Value [Abstract]
Less than 12 months - Fair Value	593
12 months or more - Fair Value	0
Total - Fair Value	593
Available for sale securities unrealized loss position - Gross Unrealized Loss [Abstract]
Less than 12 months - Gross Unrealized Loss	7
12 months or more - Gross Unrealized Loss	0
Total - Gross Unrealized Loss	$ 7