Securities (Amortized cost and fair value of debt securities by contractrual maturity) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Available-for-sale Securities
Securities available for sale, amortized cost	$ 596,744	$ 611,331
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, fair value	265,374	263,697
Debt Securities [Member]
Held-to-maturity Securities
Due in one year or less, amortized cost	0
Due after one year through five years, amortized cost	5,000
Due after five years through ten years, amortized cost	70,000
Due after ten years, amortized cost	82,076
Securities held to maturity, amortized cost	157,076
Due in one year or less, fair value	0
Due after one year through five years, fair value	5,130
Due after five years through ten years, fair value	64,375
Due after ten years, amortized cost	75,314
Securities held to maturity, fair value	144,819
Residential mortgage-backed securities [Member]
Held-to-maturity Securities
Securities held to maturity, amortized cost	7,619	7,849
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, fair value	112,678	114,679
Debt Securities [Member]
Available-for-sale Securities
Due in one year or less, amortized cost	0
Due after one year through five years, amortized cost	3,277
Due after five years through ten years, amortized cost	48,588
Due after ten years, amortized cost	10,083
Securities available for sale, amortized cost	61,948
Due in one year or less, fair value	0
Due after one year through five years, fair value	3,196
Due after five years through ten years, fair value	45,178
Due after ten years, fair value	9,533
Available-for-sale securities, fair value	57,907
Residential mortgage-backed securities [Member]
Available-for-sale Securities
Securities available for sale, amortized cost	64,662	65,795
Available-for-sale securities, fair value	62,400	62,500
Agency CMOs [Member]
Available-for-sale Securities
Securities available for sale, amortized cost	470,134	483,591
Available-for-sale securities, fair value	$ 459,484	$ 467,064