Investment Securities - Additional Information (Details) (USD $)			3 Months Ended
	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2014 Minimum	Mar. 31, 2014 Maximum	Mar. 31, 2014 Trust Preferred Securities	Mar. 31, 2014 Trust Preferred Securities Maximum
Schedule of Available for sale Securities and Held to maturity Securities [Line Items]
Carrying value of securities pledged as collateral	$ 376,742,000	$ 373,533,000
Book value of securities sold under agreements to repurchase	131,366,000	126,900,000
Investment amortized cost	1,142,437,000	1,097,226,000			6,400,000
Fair value of investments					$ 4,800,000
Percentage of fair value of investments (less than 1%)						1.00%
Spread over LIBOR			0.85%	1.57%