Investment Securities (Available-for-sale Securities with Unrealized Loss) (Details) $ in Thousands	Sep. 30, 2016 USD ($) securities	Dec. 31, 2015 USD ($) securities
Available-for-sale securities that had an unrealized loss:
Less than 12 months, fair value	$ 119,144	$ 320,460
Less than 12 months, unrealized loss	$ 693	$ 4,018
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year | securities	29	90
12 months or more, fair value	$ 49,749	$ 104,915
12 months or more, unrealized loss	$ 1,977	$ 4,781
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year | securities	25	38
Total unrealized loss position, fair value	$ 168,893	$ 425,375
Total unrealized loss	2,670	8,799
States and political subdivisions
Available-for-sale securities that had an unrealized loss:
Less than 12 months, fair value		7,662
Less than 12 months, unrealized loss		$ 38
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year | securities		8
12 months or more, fair value		$ 213
12 months or more, unrealized loss		$ 6
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year | securities		1
Total unrealized loss position, fair value		$ 7,875
Total unrealized loss		44
Residential mortgage-backed securities
Available-for-sale securities that had an unrealized loss:
Less than 12 months, fair value	119,144	303,549
Less than 12 months, unrealized loss	$ 693	$ 3,902
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year | securities	29	76
12 months or more, fair value	$ 47,071	$ 102,090
12 months or more, unrealized loss	$ 1,481	$ 4,214
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year | securities	21	33
Total unrealized loss position, fair value	$ 166,215	$ 405,639
Total unrealized loss	2,174	8,116
Commercial mortgage-backed securities
Available-for-sale securities that had an unrealized loss:
Less than 12 months, fair value		6,682
Less than 12 months, unrealized loss		$ 44
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year | securities		3
12 months or more, fair value		$ 0
12 months or more, unrealized loss		$ 0
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year | securities		0
Total unrealized loss position, fair value		$ 6,682
Total unrealized loss		44
Bank-issued trust preferred securities
Available-for-sale securities that had an unrealized loss:
Less than 12 months, fair value	0	2,129
Less than 12 months, unrealized loss	$ 0	$ 19
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year | securities	0	1
12 months or more, fair value	$ 2,571	$ 2,506
12 months or more, unrealized loss	$ 427	$ 492
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year | securities	3	3
Total unrealized loss position, fair value	$ 2,571	$ 4,635
Total unrealized loss	$ 427	511
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | securities	3
Equity securities
Available-for-sale securities that had an unrealized loss:
Less than 12 months, fair value	$ 0	438
Less than 12 months, unrealized loss	$ 0	$ 15
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year | securities	0	2
12 months or more, fair value	$ 107	$ 106
12 months or more, unrealized loss	$ 69	$ 69
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year | securities	1	1
Total unrealized loss position, fair value	$ 107	$ 544
Total unrealized loss	$ 69	$ 84
Mortgage-backed securities, issued by US government sponsored agencies
Available-for-sale securities that had an unrealized loss:
Percentage of mortgage-backed securities in unrealized loss position for more than 12 months	99.00%
Mortgage-backed securities, privately issued
Available-for-sale securities that had an unrealized loss:
Percentage of mortgage-backed securities in unrealized loss position for more than 12 months	1.00%
Number of privately issued mortgage-backed securities securities with book value less than 90% of fair value | securities	2
Fair value within book value	90.00%
Fair Value Less Than 90 Percent of Book Value [Member] | Mortgage-backed securities, privately issued
Available-for-sale securities that had an unrealized loss:
12 months or more, fair value	$ 500
Book value of privately issued mortgage-backed securities in unrealized loss position for more than 12 months	$ 700