Investment Securities (Summary of Investment Securities with Gross Unrealized Losses) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Summary of continuous unrealized loss position of securities
Less Than 12 Months, Fair Value	$ 548,723	$ 141,129
Less Than 12 Months, Gross Unrealized Losses	13,007	2,734
12 Months or More, Fair Value	73,865	86,618
12 Months or More, Gross Unrealized Losses	5,491	6,351
Total, Fair Value	622,588	227,747
Total, Gross Unrealized Losses	18,498	9,085
Government sponsored agencies [Member]
Summary of continuous unrealized loss position of securities
Less Than 12 Months, Fair Value	47,352	46,103
Less Than 12 Months, Gross Unrealized Losses	205	213
12 Months or More, Fair Value	14,031	0
12 Months or More, Gross Unrealized Losses	177	0
Total, Fair Value	61,383	46,103
Total, Gross Unrealized Losses	382	213
State and political subdivisions [Member]
Summary of continuous unrealized loss position of securities
Less Than 12 Months, Fair Value	126,345	70,675
Less Than 12 Months, Gross Unrealized Losses	6,475	2,257
12 Months or More, Fair Value	19,074	8,046
12 Months or More, Gross Unrealized Losses	378	1,110
Total, Fair Value	145,419	78,721
Total, Gross Unrealized Losses	6,853	3,367
Residential mortgage-backed securities [Member]
Summary of continuous unrealized loss position of securities
Less Than 12 Months, Fair Value	274,076	273
Less Than 12 Months, Gross Unrealized Losses	5,097	1
12 Months or More, Fair Value	0	1,305
12 Months or More, Gross Unrealized Losses	0	8
Total, Fair Value	274,076	1,578
Total, Gross Unrealized Losses	5,097	9
Collateralized mortgage obligations [Member]
Summary of continuous unrealized loss position of securities
Less Than 12 Months, Fair Value	84,995	19,331
Less Than 12 Months, Gross Unrealized Losses	1,127	10
12 Months or More, Fair Value	14,684	36,835
12 Months or More, Gross Unrealized Losses	512	172
Total, Fair Value	99,679	56,166
Total, Gross Unrealized Losses	1,639	182
Corporate bonds [Member]
Summary of continuous unrealized loss position of securities
Less Than 12 Months, Fair Value	14,931	4,747
Less Than 12 Months, Gross Unrealized Losses	78	253
12 Months or More, Fair Value	19,826	34,707
12 Months or More, Gross Unrealized Losses	174	286
Total, Fair Value	34,757	39,454
Total, Gross Unrealized Losses	252	539
Trust preferred securities [Member]
Summary of continuous unrealized loss position of securities
Less Than 12 Months, Fair Value	0	0
Less Than 12 Months, Gross Unrealized Losses	0	0
12 Months or More, Fair Value	6,250	5,725
12 Months or More, Gross Unrealized Losses	4,250	4,775
Total, Fair Value	6,250	5,725
Total, Gross Unrealized Losses	4,250	4,775
Preferred stock [Member]
Summary of continuous unrealized loss position of securities
Less Than 12 Months, Fair Value	1,024
Less Than 12 Months, Gross Unrealized Losses	25
12 Months or More, Fair Value	0
12 Months or More, Gross Unrealized Losses	0
Total, Fair Value	1,024
Total, Gross Unrealized Losses	$ 25