Investment Securities Available-for-sale Securities with Unrealized Losses (Details) (USD $)	12 Months Ended
	Dec. 31, 2013 securities	Dec. 31, 2012 securities
Available-for-sale securities that had an unrealized loss:
Fair value of securities in unrealized loss position less than 12 months	$ 347,736,000	$ 149,865,000
Unrealized loss less than 12 months	18,237,000	2,469,000
Number of securities at an unrealized loss position less than 12 months	102	40
Fair value of securities in unrealized loss more than 12 months	75,725,000	95,483,000
Unrealized loss more than 12 months	7,301,000	8,190,000
Number of securities at an unrealized loss position more than 12 months	38	26
Fair value of securities in unrealized loss	423,461,000	245,348,000
Unrealized loss	25,538,000	10,659,000
Other-than-temporary impairments	0
Mortgage-backed securities issued by US Government sponsored agencies
Available-for-sale securities that had an unrealized loss:
Percentage of mortgage-backed securities in unrealized loss position for less than 12 months	96.00%
Mortgage-backed securities privately issued
Available-for-sale securities that had an unrealized loss:
Number of securities at an unrealized loss position less than 12 months	5
Securities in unrealized loss position with fair value less than 90% of book value	3
Percentage of mortgage-backed securities in unrealized loss position for less than 12 months	4.00%
Fair value within book value	90.00%
U.S. Treasury and government agencies
Available-for-sale securities that had an unrealized loss:
Fair value of securities in unrealized loss position less than 12 months	0	0
Unrealized loss less than 12 months	0	0
Number of securities at an unrealized loss position less than 12 months	0	0
Fair value of securities in unrealized loss more than 12 months	0	0
Unrealized loss more than 12 months	0	0
Number of securities at an unrealized loss position more than 12 months	0	0
Fair value of securities in unrealized loss	0	0
Unrealized loss	0	0
U.S. government sponsored agencies
Available-for-sale securities that had an unrealized loss:
Fair value of securities in unrealized loss position less than 12 months	0	0
Unrealized loss less than 12 months	0	0
Number of securities at an unrealized loss position less than 12 months	0	0
Fair value of securities in unrealized loss more than 12 months	0	0
Unrealized loss more than 12 months	0	0
Number of securities at an unrealized loss position more than 12 months	0	0
Fair value of securities in unrealized loss	0	0
Unrealized loss	0	0
States and political subdivisions
Available-for-sale securities that had an unrealized loss:
Fair value of securities in unrealized loss position less than 12 months	15,848,000	4,558,000
Unrealized loss less than 12 months	659,000	82,000
Number of securities at an unrealized loss position less than 12 months	22	8
Fair value of securities in unrealized loss more than 12 months	6,180,000	0
Unrealized loss more than 12 months	368,000	0
Number of securities at an unrealized loss position more than 12 months	10	0
Fair value of securities in unrealized loss	22,028,000	4,558,000
Unrealized loss	1,027,000	82,000
Residential mortgage-backed securities
Available-for-sale securities that had an unrealized loss:
Fair value of securities in unrealized loss position less than 12 months	310,315,000	135,250,000
Unrealized loss less than 12 months	16,709,000	2,326,000
Number of securities at an unrealized loss position less than 12 months	75	28
Fair value of securities in unrealized loss more than 12 months	57,440,000	89,958,000
Unrealized loss more than 12 months	5,811,000	7,441,000
Number of securities at an unrealized loss position more than 12 months	20	20
Fair value of securities in unrealized loss	367,755,000	225,208,000
Unrealized loss	22,520,000	9,767,000
Commercial mortgage-backed securities
Available-for-sale securities that had an unrealized loss:
Fair value of securities in unrealized loss position less than 12 months	19,560,000	7,681,000
Unrealized loss less than 12 months	779,000	43,000
Number of securities at an unrealized loss position less than 12 months	4	2
Fair value of securities in unrealized loss more than 12 months	7,205,000	0
Unrealized loss more than 12 months	447,000	0
Number of securities at an unrealized loss position more than 12 months	2	0
Fair value of securities in unrealized loss	26,765,000	7,681,000
Unrealized loss	1,226,000	43,000
Bank-issued trust preferred securities
Available-for-sale securities that had an unrealized loss:
Fair value of securities in unrealized loss position less than 12 months	2,013,000	2,376,000
Unrealized loss less than 12 months	90,000	18,000
Number of securities at an unrealized loss position less than 12 months	1	2
Fair value of securities in unrealized loss more than 12 months	4,803,000	5,434,000
Unrealized loss more than 12 months	589,000	664,000
Number of securities at an unrealized loss position more than 12 months	4	5
Fair value of securities in unrealized loss	6,816,000	7,810,000
Unrealized loss	679,000	682,000
Number of available-for-sale securities in unrealized loss position	4
Equity securities
Available-for-sale securities that had an unrealized loss:
Fair value of securities in unrealized loss position less than 12 months	0	0
Unrealized loss less than 12 months	0	0
Number of securities at an unrealized loss position less than 12 months	0	0
Fair value of securities in unrealized loss more than 12 months	97,000	91,000
Unrealized loss more than 12 months	86,000	85,000
Number of securities at an unrealized loss position more than 12 months	2	1
Fair value of securities in unrealized loss	97,000	91,000
Unrealized loss	86,000	85,000
Fair Value Less Than 90 Percent of Book Value | Mortgage-backed securities privately issued
Available-for-sale securities that had an unrealized loss:
Fair value of securities in unrealized loss more than 12 months	1,600,000
Mortgage-backed securities in unrealized loss position for less than 12 months, aggregate book value	$ 1,800,000