Investment Securities (Available-for-sale Securities with Unrealized Loss) (Details) $ in Thousands	Sep. 30, 2015 USD ($) securities	Dec. 31, 2014 USD ($) securities
Available-for-sale securities that had an unrealized loss:
Less than 12 months, fair value	$ 115,150	$ 116,660
Less than 12 months, unrealized loss	$ 1,258	$ 1,105
Less than 12 months, no. of securities | securities	45	27
12 months or more, fair value	$ 99,657	$ 244,021
12 months or more, unrealized loss	$ 3,718	$ 7,675
12 months or more, no. of securities | securities	36	73
Total unrealized loss position, fair value	$ 214,807	$ 360,681
Total unrealized loss	4,976	8,780
States and political subdivisions
Available-for-sale securities that had an unrealized loss:
Less than 12 months, fair value	7,453	2,602
Less than 12 months, unrealized loss	$ 71	$ 12
Less than 12 months, no. of securities | securities	15	4
12 months or more, fair value	$ 213	$ 5,788
12 months or more, unrealized loss	$ 8	$ 47
12 months or more, no. of securities | securities	1	8
Total unrealized loss position, fair value	$ 7,666	$ 8,390
Total unrealized loss	79	59
Residential mortgage-backed securities
Available-for-sale securities that had an unrealized loss:
Less than 12 months, fair value	105,219	114,018
Less than 12 months, unrealized loss	$ 1,167	$ 1,091
Less than 12 months, no. of securities | securities	28	21
12 months or more, fair value	$ 96,747	$ 216,224
12 months or more, unrealized loss	$ 3,234	$ 6,773
12 months or more, no. of securities | securities	31	57
Total unrealized loss position, fair value	$ 201,966	$ 330,242
Total unrealized loss	4,401	7,864
Commercial mortgage-backed securities
Available-for-sale securities that had an unrealized loss:
Less than 12 months, fair value	0	0
Less than 12 months, unrealized loss	$ 0	$ 0
Less than 12 months, no. of securities | securities	0	0
12 months or more, fair value	$ 0	$ 19,404
12 months or more, unrealized loss	$ 0	$ 286
12 months or more, no. of securities | securities	0	4
Total unrealized loss position, fair value	$ 0	$ 19,404
Total unrealized loss	0	286
Bank-issued trust preferred securities
Available-for-sale securities that had an unrealized loss:
Less than 12 months, fair value	2,139	0
Less than 12 months, unrealized loss	$ 3	$ 0
Less than 12 months, no. of securities | securities	0	0
12 months or more, fair value	$ 2,595	$ 2,509
12 months or more, unrealized loss	$ 403	$ 490
12 months or more, no. of securities | securities	3	3
Total unrealized loss position, fair value	$ 4,734	$ 2,509
Total unrealized loss	$ 406	490
Number of bank-issued trust preferred securities in unrealized loss position for twelve months or more | securities	3
Equity securities
Available-for-sale securities that had an unrealized loss:
Less than 12 months, fair value	$ 339	40
Less than 12 months, unrealized loss	$ 17	$ 2
Less than 12 months, no. of securities | securities	2	2
12 months or more, fair value	$ 102	$ 96
12 months or more, unrealized loss	$ 73	$ 79
12 months or more, no. of securities | securities	1	1
Total unrealized loss position, fair value	$ 441	$ 136
Total unrealized loss	$ 90	$ 81
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	97.00%
Mortgage-backed securities, privately issued
Available-for-sale securities that had an unrealized loss:
Less than 12 months, no. of securities | securities	3
Percentage of mortgage-backed securities in unrealized loss position for more than 12 months	3.00%
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