Securities (Amortized cost and fair value of securities) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Available-for-sale Securities
Available-for-sale securities, amortized cost basis	$ 487,818	$ 533,999
Available-for-sale securities, gross unrealized gains	4,369	2,917
Available-for-sale securities, gross unrealized losses	(6,162)	(8,878)
Available-for-sale securities, fair value	486,025us-gaap_AvailableForSaleSecurities	528,038us-gaap_AvailableForSaleSecurities
Held-to-maturity Securities
Held-to-maturity securities, amortized cost	323,082us-gaap_HeldToMaturitySecurities	324,994us-gaap_HeldToMaturitySecurities
Held-to-maturity securities, gross unrealized gains	3,134	1,299
Held-to-maturity securities, gross unrealized losses	(3,160)	(6,370)
Held-to-maturity securities, fair value	323,056	319,923
U.S. Government agency securities [Member]
Held-to-maturity Securities
Held-to-maturity securities, amortized cost	149,117	149,112
Held-to-maturity securities, gross unrealized gains	321	0
Held-to-maturity securities, gross unrealized losses	(2,212)	(4,658)
Held-to-maturity securities, fair value	147,226	144,454
Residential mortgage-backed securities [Member]
Held-to-maturity Securities
Held-to-maturity securities, amortized cost	12,281	14,226
Held-to-maturity securities, gross unrealized gains	312	480
Held-to-maturity securities, gross unrealized losses	0	0
Held-to-maturity securities, fair value	12,593	14,706
Agency CMOs [Member]
Held-to-maturity Securities
Held-to-maturity securities, amortized cost	146,981	146,952
Held-to-maturity securities, gross unrealized gains	2,309	649
Held-to-maturity securities, gross unrealized losses	(948)	(1,711)
Held-to-maturity securities, fair value	148,342	145,890
Corporate debt securities [Member]
Held-to-maturity Securities
Held-to-maturity securities, amortized cost	5,000	5,000
Held-to-maturity securities, gross unrealized gains	41	63
Held-to-maturity securities, gross unrealized losses	0	0
Held-to-maturity securities, fair value	5,041	5,063
Municipal securities [Member]
Held-to-maturity Securities
Held-to-maturity securities, amortized cost	9,703	9,704
Held-to-maturity securities, gross unrealized gains	151	107
Held-to-maturity securities, gross unrealized losses	0	(1)
Held-to-maturity securities, fair value	9,854	9,810
U.S. Government agency securities [Member]
Available-for-sale Securities
Available-for-sale securities, amortized cost basis	33,996	33,995
Available-for-sale securities, gross unrealized gains	0	0
Available-for-sale securities, gross unrealized losses	(455)	(1,207)
Available-for-sale securities, fair value	33,541	32,788
Residential mortgage-backed securities [Member]
Available-for-sale Securities
Available-for-sale securities, amortized cost basis	58,453	60,196
Available-for-sale securities, gross unrealized gains	498	442
Available-for-sale securities, gross unrealized losses	(222)	(489)
Available-for-sale securities, fair value	58,729	60,149
Agency CMOs [Member]
Available-for-sale Securities
Available-for-sale securities, amortized cost basis	365,381	409,823
Available-for-sale securities, gross unrealized gains	3,541	2,250
Available-for-sale securities, gross unrealized losses	(5,403)	(7,064)
Available-for-sale securities, fair value	363,519	405,009
Municipal securities [Member]
Available-for-sale Securities
Available-for-sale securities, amortized cost basis	29,988	29,985
Available-for-sale securities, gross unrealized gains	330	225
Available-for-sale securities, gross unrealized losses	(82)	(118)
Available-for-sale securities, fair value	$ 30,236	$ 30,092

Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt securities classified as available-for-sale.

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