Securities (Amortized cost and fair value of securities) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Available-for-sale Securities
Available-for-sale securities, amortized cost basis	$ 656,902	$ 664,139
Securities available for sale, gross unrealized gains	3,114	11,967
Securities available for sale, gross unrealized losses	(15,348)	(997)
Securities available for sale, fair value	644,668	675,109
Held-to-maturity Securities
Securities held to maturity, amortized cost	218,794	269,783
Securities held to maturity, gross unrealized gains	1,623	4,251
Securities held to maturity, gross unrealized losses	(9,662)	(363)
Securities held to maturity, fair value	210,755	273,671
Debt Securities [Member]
Held-to-maturity Securities
Securities held to maturity, amortized cost	157,067
U.S. Government agency securities [Member]
Held-to-maturity Securities
Securities held to maturity, amortized cost	149,089	178,926
Securities held to maturity, gross unrealized gains	0	700
Securities held to maturity, gross unrealized losses	(9,518)	(363)
Securities held to maturity, fair value	139,571	179,263
Residential mortgage-backed securities [Member]
Held-to-maturity Securities
Securities held to maturity, amortized cost	18,024	23,827
Securities held to maturity, gross unrealized gains	1,089	1,889
Securities held to maturity, gross unrealized losses	0	0
Securities held to maturity, fair value	19,113	25,716
Agency CMOs [Member]
Held-to-maturity Securities
Securities held to maturity, amortized cost	43,703	49,051
Securities held to maturity, gross unrealized gains	476	1,587
Securities held to maturity, gross unrealized losses	0	0
Securities held to maturity, fair value	44,179	50,638
Corporate debt securities [Member]
Held-to-maturity Securities
Securities held to maturity, amortized cost	5,000	15,000
Securities held to maturity, gross unrealized gains	55	13
Securities held to maturity, gross unrealized losses	0	0
Securities held to maturity, fair value	5,055	15,013
Municipal securities [Member]
Held-to-maturity Securities
Securities held to maturity, amortized cost	2,978	2,979
Securities held to maturity, gross unrealized gains	3	62
Securities held to maturity, gross unrealized losses	(144)	0
Securities held to maturity, fair value	2,837	3,041
Debt Securities [Member]
Available-for-sale Securities
Available-for-sale securities, amortized cost basis	60,889
U.S. Government agency securities [Member]
Available-for-sale Securities
Available-for-sale securities, amortized cost basis	33,994	33,994
Securities available for sale, gross unrealized gains	0	19
Securities available for sale, gross unrealized losses	(2,991)	(252)
Securities available for sale, fair value	31,003	33,761
Residential mortgage-backed securities [Member]
Available-for-sale Securities
Available-for-sale securities, amortized cost basis	68,949	55,614
Securities available for sale, gross unrealized gains	0	1,596
Securities available for sale, gross unrealized losses	(1,844)	0
Securities available for sale, fair value	67,105	57,210
Agency CMOs [Member]
Available-for-sale Securities
Available-for-sale securities, amortized cost basis	527,064	547,641
Securities available for sale, gross unrealized gains	3,114	9,971
Securities available for sale, gross unrealized losses	(9,349)	(745)
Securities available for sale, fair value	520,829	556,867
Municipal securities [Member]
Available-for-sale Securities
Available-for-sale securities, amortized cost basis	26,895	26,890
Securities available for sale, gross unrealized gains	0	381
Securities available for sale, gross unrealized losses	(1,164)	0
Securities available for sale, fair value	25,731
Fair Value, Measurements, Recurring [Member] \| Municipal securities [Member]
Available-for-sale Securities
Securities available for sale, fair value		$ 27,271

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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