Securities (Amortized cost and fair value of securities) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2014	Dec. 31, 2013
Available-for-sale Securities
Available-for-sale securities, amortized cost basis	$ 596,744	$ 611,331
Securities available for sale, gross unrealized gains	1,599	1,141
Securities available for sale, gross unrealized losses	(18,552)	(26,549)
Available-for-sale securities, fair value	579,791	585,923
Held-to-maturity Securities
Securities held to maturity, amortized cost	280,096	283,814
Securities held to maturity, gross unrealized gains	605	597
Securities held to maturity, gross unrealized losses	(15,327)	(20,714)
Securities held to maturity, fair value	265,374	263,697
U.S. Government agency securities [Member]
Held-to-maturity Securities
Securities held to maturity, amortized cost	149,100	149,096
Securities held to maturity, gross unrealized gains	0	0
Securities held to maturity, gross unrealized losses	(12,317)	(16,082)
Securities held to maturity, fair value	136,783	133,014
Residential mortgage-backed securities [Member]
Held-to-maturity Securities
Securities held to maturity, amortized cost	7,619	7,849
Securities held to maturity, gross unrealized gains	258	197
Securities held to maturity, gross unrealized losses	0	0
Securities held to maturity, fair value	7,877	8,046
Agency CMOs [Member]
Held-to-maturity Securities
Securities held to maturity, amortized cost	115,401	118,893
Securities held to maturity, gross unrealized gains	207	251
Securities held to maturity, gross unrealized losses	(2,930)	(4,465)
Securities held to maturity, fair value	112,678	114,679
Corporate debt securities [Member]
Held-to-maturity Securities
Securities held to maturity, amortized cost	5,000	5,000
Securities held to maturity, gross unrealized gains	130	149
Securities held to maturity, gross unrealized losses	0	0
Securities held to maturity, fair value	5,130	5,149
Municipal securities [Member]
Held-to-maturity Securities
Securities held to maturity, amortized cost	2,976	2,976
Securities held to maturity, gross unrealized gains	10	0
Securities held to maturity, gross unrealized losses	(80)	(167)
Securities held to maturity, fair value	2,906	2,809
U.S. Government agency securities [Member]
Available-for-sale Securities
Available-for-sale securities, amortized cost basis	33,995	33,995
Securities available for sale, gross unrealized gains	0	0
Securities available for sale, gross unrealized losses	(3,107)	(4,069)
Available-for-sale securities, fair value	30,888	29,926
Residential mortgage-backed securities [Member]
Available-for-sale Securities
Available-for-sale securities, amortized cost basis	64,662	65,795
Securities available for sale, gross unrealized gains	0	0
Securities available for sale, gross unrealized losses	(2,262)	(3,295)
Available-for-sale securities, fair value	62,400	62,500
Agency CMOs [Member]
Available-for-sale Securities
Available-for-sale securities, amortized cost basis	470,134	483,591
Securities available for sale, gross unrealized gains	1,587	1,141
Securities available for sale, gross unrealized losses	(12,237)	(17,668)
Available-for-sale securities, fair value	459,484	467,064
Municipal securities [Member]
Available-for-sale Securities
Available-for-sale securities, amortized cost basis	27,953	27,950
Securities available for sale, gross unrealized gains	12	0
Securities available for sale, gross unrealized losses	(946)	(1,517)
Available-for-sale securities, fair value	$ 27,019	$ 26,433