Securities (Securities by Contractual Maturity) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012		Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Available for sale debt securities maturities within 1 year amortized cost	$ 99,742
Available for sale debt securities maturities 1-5 years amortized cost	249,600
Available for sale debt securities maturities 5-10 years amortized cost	34,715
Available for sale debt securities maturities after 10 years amortized cost	40,137
Available for sale debt securities maturities total amortized cost	424,194
Available for sale debt securities maturities within 1 year weighted average yield	4.31%
Available for sale debt securities maturities 1-5 years weighted average yield	4.07%
Available for sale debt securities maturities 5-10 years weighted average yield	2.48%
Available for sale debt securities maturities after 10 years weighted average yield	1.83%
Available for sale debt securities maturities total weighted average yield	3.78%
Available for sale debt securities maturities within 1 year fair value	103,908
Available for sale debt securities maturities 1-5 years fair value	258,863
Available for sale debt securities maturities 5-10 years fair value	37,021
Available for sale debt securities maturities after 10 years fair value	40,497
Available for sale debt securities fair value	440,289
Held to maturity debt securities maturities total amortized cost	43,569	[1]	52,139	[1]
Held to maturity debt securities maturities within 1 year fair value	10,992
Held to maturity debt securities maturities 1-5 years fair value	23,159
Held to maturity debt securities maturities 5-10 years fair value	8,657
Held to maturity debt securities maturities after 10 years fair value	2,223
Held to maturity securities fair value	45,031		52,499
Obligations of U.S. government-sponsored enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale debt securities maturities within 1 year amortized cost	0
Available for sale debt securities maturities 1-5 years amortized cost	29,451
Available for sale debt securities maturities 5-10 years amortized cost	0
Available for sale debt securities maturities after 10 years amortized cost	0
Available for sale debt securities maturities total amortized cost	29,451
Available for sale debt securities maturities within 1 year weighted average yield	0.00%
Available for sale debt securities maturities 1-5 years weighted average yield	5.40%
Available for sale debt securities maturities 5-10 years weighted average yield	0.00%
Available for sale debt securities maturities after 10 years weighted average yield	0.00%
Available for sale debt securities maturities total weighted average yield	5.40%
Available for sale debt securities fair value	32,035		32,833
Mortgage-backed securities issued by U.S. government-sponsored agencies and U.S. government-sponsored enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale debt securities maturities within 1 year amortized cost	92,691
Available for sale debt securities maturities 1-5 years amortized cost	145,406
Available for sale debt securities maturities 5-10 years amortized cost	33,912
Available for sale debt securities maturities after 10 years amortized cost	5,423
Available for sale debt securities maturities total amortized cost	277,432
Available for sale debt securities maturities within 1 year weighted average yield	4.27%
Available for sale debt securities maturities 1-5 years weighted average yield	3.83%
Available for sale debt securities maturities 5-10 years weighted average yield	2.44%
Available for sale debt securities maturities after 10 years weighted average yield	2.54%
Available for sale debt securities maturities total weighted average yield	3.78%
Available for sale debt securities fair value	295,826		389,658
Held to maturity debt securities maturities within 1 year amortized cost	10,635
Held to maturity debt securities maturities 1-5 years amortized cost	22,407
Held to maturity debt securities maturities 5-10 years amortized cost	8,376
Held to maturity debt securities maturities after 10 years amortized cost	2,151
Held to maturity debt securities maturities total amortized cost	43,569	[1]	52,139	[1]
Held to maturity debt securities maturities within 1 year weighted average yield	2.48%
Held to maturity debt securities maturities 1-5 years weighted average yield	2.36%
Held to maturity debt securities maturities 5-10 years weighted average yield	2.24%
Held to maturity debt securities maturities after 10 years weighted average yield	1.19%
Held to maturity debt securities maturities total weighted average yield	2.31%
Held to maturity securities fair value	45,031		52,499
States and political subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale debt securities maturities within 1 year amortized cost	3,852
Available for sale debt securities maturities 1-5 years amortized cost	64,045
Available for sale debt securities maturities 5-10 years amortized cost	803
Available for sale debt securities maturities after 10 years amortized cost	0
Available for sale debt securities maturities total amortized cost	68,700
Available for sale debt securities maturities within 1 year weighted average yield	3.62%
Available for sale debt securities maturities 1-5 years weighted average yield	3.91%
Available for sale debt securities maturities 5-10 years weighted average yield	3.81%
Available for sale debt securities maturities after 10 years weighted average yield	0.00%
Available for sale debt securities maturities total weighted average yield	3.89%
Available for sale debt securities fair value	73,613		79,493
Trust preferred securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale debt securities maturities within 1 year amortized cost	0	[1]
Available for sale debt securities maturities 1-5 years amortized cost	0	[1]
Available for sale debt securities maturities 5-10 years amortized cost	0	[1]
Available for sale debt securities maturities after 10 years amortized cost	34,714	[1]
Available for sale debt securities maturities total amortized cost	34,714	[1]
Available for sale debt securities maturities within 1 year weighted average yield	0.00%
Available for sale debt securities maturities 1-5 years weighted average yield	0.00%
Available for sale debt securities maturities 5-10 years weighted average yield	0.00%
Available for sale debt securities maturities after 10 years weighted average yield	1.72%
Available for sale debt securities maturities total weighted average yield	1.72%
Corporate bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale debt securities maturities within 1 year amortized cost	3,199
Available for sale debt securities maturities 1-5 years amortized cost	10,698
Available for sale debt securities maturities 5-10 years amortized cost	0
Available for sale debt securities maturities after 10 years amortized cost	0
Available for sale debt securities maturities total amortized cost	13,897
Available for sale debt securities maturities within 1 year weighted average yield	6.31%
Available for sale debt securities maturities 1-5 years weighted average yield	4.68%
Available for sale debt securities maturities 5-10 years weighted average yield	0.00%
Available for sale debt securities maturities after 10 years weighted average yield	0.00%
Available for sale debt securities maturities total weighted average yield	5.05%
Available for sale debt securities fair value	$ 14,449		$ 14,282

[1] Net of other-than-temporary impairment losses.