Securities (Amortized cost and fair value of securities) (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2014	Dec. 31, 2013
Available-for-sale Securities
Available-for-sale securities, amortized cost basis	$ 572,611	$ 611,331
Securities available for sale, gross unrealized gains	1,611	1,141
Securities available for sale, gross unrealized losses	(17,124)	(26,549)
Available-for-sale securities, fair value	557,098	585,923
Held-to-maturity Securities
Securities held to maturity, amortized cost	330,417	283,814
Securities held to maturity, gross unrealized gains	817	597
Securities held to maturity, gross unrealized losses	(11,094)	(20,714)
Securities held to maturity, fair value	320,140	263,697
U.S. Government agency securities [Member]
Held-to-maturity Securities
Securities held to maturity, amortized cost	149,109	149,096
Securities held to maturity, gross unrealized gains	0	0
Securities held to maturity, gross unrealized losses	(8,089)	(16,082)
Securities held to maturity, fair value	141,020	133,014
Residential mortgage-backed securities [Member]
Held-to-maturity Securities
Securities held to maturity, amortized cost	14,387	7,849
Securities held to maturity, gross unrealized gains	344	197
Securities held to maturity, gross unrealized losses	(45)	0
Securities held to maturity, fair value	14,686	8,046
Agency CMOs [Member]
Held-to-maturity Securities
Securities held to maturity, amortized cost	152,215	118,893
Securities held to maturity, gross unrealized gains	307	251
Securities held to maturity, gross unrealized losses	(2,949)	(4,465)
Securities held to maturity, fair value	149,573	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	89	149
Securities held to maturity, gross unrealized losses	0	0
Securities held to maturity, fair value	5,089	5,149
Municipal securities [Member]
Held-to-maturity Securities
Securities held to maturity, amortized cost	9,706	2,976
Securities held to maturity, gross unrealized gains	77	0
Securities held to maturity, gross unrealized losses	(11)	(167)
Securities held to maturity, fair value	9,772	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	(2,168)	(4,069)
Available-for-sale securities, fair value	31,827	29,926
Residential mortgage-backed securities [Member]
Available-for-sale Securities
Available-for-sale securities, amortized cost basis	61,585	65,795
Securities available for sale, gross unrealized gains	26	0
Securities available for sale, gross unrealized losses	(1,109)	(3,295)
Available-for-sale securities, fair value	60,502	62,500
Agency CMOs [Member]
Available-for-sale Securities
Available-for-sale securities, amortized cost basis	447,049	483,591
Securities available for sale, gross unrealized gains	1,408	1,141
Securities available for sale, gross unrealized losses	(13,528)	(17,668)
Available-for-sale securities, fair value	434,929	467,064
Municipal securities [Member]
Available-for-sale Securities
Available-for-sale securities, amortized cost basis	29,982	27,950
Securities available for sale, gross unrealized gains	177	0
Securities available for sale, gross unrealized losses	(319)	(1,517)
Available-for-sale securities, fair value	$ 29,840	$ 26,433