Securities (Securities by Contractual Maturity) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012		Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Available for sale debt securities maturities within 1 year amortized cost	$ 97,690
Available for sale debt securities maturities 1-5 years amortized cost	265,500
Available for sale debt securities maturities 5-10 years amortized cost	45,428
Available for sale debt securities maturities after 10 years amortized cost	44,115
Available for sale debt securities maturities total amortized cost	452,733
Available for sale debt securities maturities within 1 year weighted average yield	4.33%
Available for sale debt securities maturities 1-5 years weighted average yield	4.11%
Available for sale debt securities maturities 5-10 years weighted average yield	2.63%
Available for sale debt securities maturities after 10 years weighted average yield	1.94%
Available for sale debt securities maturities total weighted average yield	3.80%
Available for sale debt securities maturities within 1 year fair value	101,209
Available for sale debt securities maturities 1-5 years fair value	275,084
Available for sale debt securities maturities 5-10 years fair value	48,189
Available for sale debt securities maturities after 10 years fair value	44,685
Available for sale debt securities fair value	469,167
Held to maturity debt securities maturities total amortized cost	47,026	[1]	52,139	[1]
Held to maturity debt securities maturities within 1 year fair value	9,961
Held to maturity debt securities maturities 1-5 years fair value	23,597
Held to maturity debt securities maturities 5-10 years fair value	10,901
Held to maturity debt securities maturities after 10 years fair value	3,761
Held to maturity securities fair value	48,220		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	29,443
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	29,443
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	5.41%
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	5.41%
Available for sale debt securities fair value	32,319		32,833
Held to maturity debt securities maturities within 1 year amortized cost	9,714
Held to maturity debt securities maturities 1-5 years amortized cost	23,013
Held to maturity debt securities maturities 5-10 years amortized cost	10,631
Held to maturity debt securities maturities after 10 years amortized cost	3,668
Held to maturity debt securities maturities total amortized cost	47,026
Held to maturity debt securities maturities within 1 year weighted average yield	2.67%
Held to maturity debt securities maturities 1-5 years weighted average yield	2.56%
Held to maturity debt securities maturities 5-10 years weighted average yield	2.44%
Held to maturity debt securities maturities after 10 years weighted average yield	1.49%
Held to maturity debt securities maturities total weighted average yield	2.47%
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	90,411
Available for sale debt securities maturities 1-5 years amortized cost	161,311
Available for sale debt securities maturities 5-10 years amortized cost	44,625
Available for sale debt securities maturities after 10 years amortized cost	9,410
Available for sale debt securities maturities total amortized cost	305,757
Available for sale debt securities maturities within 1 year weighted average yield	4.29%
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	2.61%
Available for sale debt securities maturities after 10 years weighted average yield	2.34%
Available for sale debt securities maturities total weighted average yield	3.78%
Available for sale debt securities fair value	324,292		389,658
Held to maturity debt securities maturities total amortized cost	47,026	[1]	52,139	[1]
Held to maturity securities fair value	48,220		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	4,083
Available for sale debt securities maturities 1-5 years amortized cost	64,053
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	68,939
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	3.90%
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	73,723		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	34,705	[1]
Available for sale debt securities maturities total amortized cost	34,705	[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	1.83%
Available for sale debt securities maturities total weighted average yield	1.83%
Corporate bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale debt securities maturities within 1 year amortized cost	3,196
Available for sale debt securities maturities 1-5 years amortized cost	10,693
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	13,889
Available for sale debt securities maturities within 1 year weighted average yield	6.32%
Available for sale debt securities maturities 1-5 years weighted average yield	4.73%
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	5.09%
Available for sale debt securities fair value	$ 14,446		$ 14,282

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