Securities (Amortized cost and fair value of securities) (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Available-for-sale Securities
Available-for-sale securities, amortized cost basis	$ 404,026	$ 533,999
Available-for-sale securities, gross unrealized gains	2,983	2,917
Available-for-sale securities, gross unrealized losses	(5,399)	(8,878)
Available-for-sale securities, fair value	401,610	528,038
Held-to-maturity Securities
Held-to-maturity securities, amortized cost	325,378	324,994
Held-to-maturity securities, gross unrealized gains	3,586	1,299
Held-to-maturity securities, gross unrealized losses	(2,554)	(6,370)
Held-to-maturity securities, fair value	326,410	319,923
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	(302)	(1,207)
Available-for-sale securities, fair value	33,694	32,788
Held-to-maturity Securities
Held-to-maturity securities, amortized cost	139,139	149,112
Held-to-maturity securities, gross unrealized gains	357	0
Held-to-maturity securities, gross unrealized losses	(1,375)	(4,658)
Held-to-maturity securities, fair value	138,121	144,454
Residential mortgage-backed securities [Member]
Available-for-sale Securities
Available-for-sale securities, amortized cost basis	54,963	60,196
Available-for-sale securities, gross unrealized gains	511	442
Available-for-sale securities, gross unrealized losses	(351)	(489)
Available-for-sale securities, fair value	55,123	60,149
Held-to-maturity Securities
Held-to-maturity securities, amortized cost	11,674	14,226
Held-to-maturity securities, gross unrealized gains	266	480
Held-to-maturity securities, gross unrealized losses	0	0
Held-to-maturity securities, fair value	11,940	14,706
Agency CMOs [Member]
Available-for-sale Securities
Available-for-sale securities, amortized cost basis	285,073	409,823
Available-for-sale securities, gross unrealized gains	2,208	2,250
Available-for-sale securities, gross unrealized losses	(4,620)	(7,064)
Available-for-sale securities, fair value	282,661	405,009
Held-to-maturity Securities
Held-to-maturity securities, amortized cost	164,865	146,952
Held-to-maturity securities, gross unrealized gains	2,855	649
Held-to-maturity securities, gross unrealized losses	(1,153)	(1,711)
Held-to-maturity securities, fair value	166,567	145,890
Corporate debt securities [Member]
Held-to-maturity Securities
Held-to-maturity securities, amortized cost		5,000
Held-to-maturity securities, gross unrealized gains		63
Held-to-maturity securities, gross unrealized losses		0
Held-to-maturity securities, fair value		5,063
Municipal securities [Member]
Available-for-sale Securities
Available-for-sale securities, amortized cost basis	29,994	29,985
Available-for-sale securities, gross unrealized gains	264	225
Available-for-sale securities, gross unrealized losses	(126)	(118)
Available-for-sale securities, fair value	30,132	30,092
Held-to-maturity Securities
Held-to-maturity securities, amortized cost	9,700	9,704
Held-to-maturity securities, gross unrealized gains	108	107
Held-to-maturity securities, gross unrealized losses	(26)	(1)
Held-to-maturity securities, fair value	$ 9,782	$ 9,810