AFS Securities (Amortized cost and fair value of AFS securities by contractual maturity) (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]
Maturing, Due in One Year or Less	$ 30,337
Maturing, After One Year But Within Five Years	81,853
Maturing, After Five Years But Within Ten Years	83,728
Maturing, After Ten Years	30,318
Securities With Variable Monthly Payments or Noncontractual Maturities	359,343
Amortized Cost	585,579	$ 654,348
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Maturing, Due in One Year or Less, Fair value	30,414
Maturing, After One Year But Within Five Years, Fair value	84,966
Maturing, After Five Years But Within Ten Years, Fair value	88,857
Maturing, After Ten Years, Fair value	32,181
Securities With Variable Monthly Payments or Noncontractual Maturities, Fair value	366,045
Total, Fair value	602,463	660,136
Government sponsored enterprises [Member]
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]
Maturing, Due in One Year or Less	0
Maturing, After One Year But Within Five Years	10,032
Maturing, After Five Years But Within Ten Years	330
Maturing, After Ten Years	0
Securities With Variable Monthly Payments or Noncontractual Maturities	0
Amortized Cost	10,362	24,407
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Total, Fair value	10,371	24,345
States and political subdivisions [Member]
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]
Maturing, Due in One Year or Less	30,337
Maturing, After One Year But Within Five Years	71,821
Maturing, After Five Years But Within Ten Years	83,398
Maturing, After Ten Years	30,318
Securities With Variable Monthly Payments or Noncontractual Maturities	0
Amortized Cost	215,874	224,752
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Total, Fair value	226,047	232,217
Auction rate money market preferred [Member]
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]
Maturing, Due in One Year or Less	0
Maturing, After One Year But Within Five Years	0
Maturing, After Five Years But Within Ten Years	0
Maturing, After Ten Years	0
Securities With Variable Monthly Payments or Noncontractual Maturities	3,200
Amortized Cost	3,200	3,200
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Total, Fair value	3,119	2,866
Preferred stocks [Member]
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]
Maturing, Due in One Year or Less	0
Maturing, After One Year But Within Five Years	0
Maturing, After Five Years But Within Ten Years	0
Maturing, After Ten Years	0
Securities With Variable Monthly Payments or Noncontractual Maturities	3,800
Amortized Cost	3,800	3,800
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Total, Fair value	3,406	3,299
Mortgage-backed securities [Member]
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]
Maturing, Due in One Year or Less	0
Maturing, After One Year But Within Five Years	0
Maturing, After Five Years But Within Ten Years	0
Maturing, After Ten Years	0
Securities With Variable Monthly Payments or Noncontractual Maturities	235,480
Amortized Cost	235,480	264,109
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Total, Fair value	240,195	263,384
Collateralized mortgage obligations [Member]
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]
Maturing, Due in One Year or Less	0
Maturing, After One Year But Within Five Years	0
Maturing, After Five Years But Within Ten Years	0
Maturing, After Ten Years	0
Securities With Variable Monthly Payments or Noncontractual Maturities	116,863
Amortized Cost	116,863	134,080
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Total, Fair value	$ 119,325	$ 134,025