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Securities (Details) $ in Thousands | Jun. 30, 2015 USD ($) Position | Dec. 31, 2014 USD ($) Position
--- | --- | ---
Schedule of Available-for-sale Securities [Line Items] |  |
Amortized cost | $ 1,118,270 | $ 1,001,718
Unrealized gains | 13,247 | 14,823
Unrealized losses | (2,268) | (3,370)
Estimated fair value | 1,129,249 | 1,013,171
Amortized costs of securities available for sale pledged to secure public deposits | 1,400,000 | 1,400,000
Amortized costs of securities available for sale pledged as collateral for repurchase agreements | 172,200 | 208,800
Unrealized Loss Position, Fair Value [Abstract] |  |
Less Than 12 Months, Fair Value | 298,181 | 143,428
12 Months or Longer, Fair Value | 42,966 | 244,836
Total, Fair Value | 341,147 | 388,264
Unrealized Loss Position, Unrealized Losses [Abstract] |  |
Less than 12 months Unrealized Losses | (1,761) | (500)
12 months or longer Unrealized Losses | (507) | (2,870)
Total Unrealized Losses | $ (2,268) | $ (3,370)
Unrealized Loss Position, Number of Positions [Abstract] |  |
Less Than 12 Months, Number of Positions | Position | 64 | 59
12 Months or Longer, Number of Positions | Position | 26 | 58
Total, Number of Positions | Position | 90 | 117
Schedule of Held-to-maturity Securities [Line Items] |  |
Amortized cost | $ 454,312 | $ 454,361
Unrealized gains | 2,353 | 2,721
Unrealized losses | (2,410) | (2,088)
Estimated fair value | 454,255 | 454,994
Unrealized Loss Position, Fair Value [Abstract] |  |
Less Than 12 Months, Fair Value | 129,010 | 69,566
12 Months or Longer, Fair Value | 44,136 | 48,034
Total, Fair Value | 173,146 | 117,600
Unrealized Loss Position, Unrealized Losses [Abstract] |  |
Less Than 12 Months, Unrealized Losses | (890) | (165)
12 Months or Longer, Unrealized Losses | (1,520) | (1,923)
Total, Unrealized Losses | $ (2,410) | $ (2,088)
Unrealized Loss Position, Number of Positions [Abstract] |  |
Held-to-maturity, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year | Position | 98 | 112
Held-to-maturity, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater Than or Equal to One Year | Position | 4 | 10
Total, Number of Positions | Position | 102 | 122
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis [Abstract] |  |
Within one year | $ 13,981 |
From one to five years | 412,442 |
From five to ten years | 150,200 |
After ten years | 528,775 |
Total, Amortized Cost | 1,105,398 |
Available-for-sale Securities, Debt Maturities, Fair Value [Abstract] |  |
Within one year | 14,032 |
From one to five years | 413,423 |
From five to ten years | 152,606 |
After ten years | 533,588 |
Total, Fair Value | 1,113,649 |
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount [Abstract] |  |
Within one year | 24,317 |
From one to five years | 15,730 |
From five to ten years | 99,778 |
After ten years | 314,487 |
Amortized cost | 454,312 | $ 454,361
Held-to-maturity Securities, Debt Maturities, Fair Value [Abstract] |  |
Within one year | 24,328 |
From one to five years | 15,811 |
From five to ten years | 99,818 |
After ten years | 314,298 |
Total, Fair Value | 454,255 | 454,994
US Treasury [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Amortized cost | 10,005 | 23,041
Unrealized gains | 9 | 70
Unrealized losses | 0 | 0
Estimated fair value | 10,014 | 23,111
Federal Agency [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Amortized cost | 397,197 | 332,193
Unrealized gains | 759 | 327
Unrealized losses | (1,033) | (2,606)
Estimated fair value | 396,923 | 329,914
Unrealized Loss Position, Fair Value [Abstract] |  |
Less Than 12 Months, Fair Value | 146,403 | 66,528
12 Months or Longer, Fair Value | 29,732 | 198,151
Total, Fair Value | 176,135 | 264,679
Unrealized Loss Position, Unrealized Losses [Abstract] |  |
Less than 12 months Unrealized Losses | (765) | (226)
12 months or longer Unrealized Losses | (268) | (2,380)
Total Unrealized Losses | $ (1,033) | $ (2,606)
Unrealized Loss Position, Number of Positions [Abstract] |  |
Less Than 12 Months, Number of Positions | Position | 13 | 8
12 Months or Longer, Number of Positions | Position | 3 | 16
Total, Number of Positions | Position | 16 | 24
State & Municipal [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Amortized cost | $ 29,881 | $ 37,035
Unrealized gains | 505 | 587
Unrealized losses | (26) | (52)
Estimated fair value | 30,360 | 37,570
Unrealized Loss Position, Fair Value [Abstract] |  |
Less Than 12 Months, Fair Value | 6,184 | 8,818
12 Months or Longer, Fair Value | 0 | 1,321
Total, Fair Value | 6,184 | 10,139
Unrealized Loss Position, Unrealized Losses [Abstract] |  |
Less than 12 months Unrealized Losses | (26) | (42)
12 months or longer Unrealized Losses | 0 | (10)
Total Unrealized Losses | $ (26) | $ (52)
Unrealized Loss Position, Number of Positions [Abstract] |  |
Less Than 12 Months, Number of Positions | Position | 14 | 33
12 Months or Longer, Number of Positions | Position | 0 | 5
Total, Number of Positions | Position | 14 | 38
Mortgage-Backed [Member] |  |
Unrealized Loss Position, Fair Value [Abstract] |  |
Less Than 12 Months, Fair Value | $ 57,745 | $ 10,400
12 Months or Longer, Fair Value | 4,571 | 35,565
Total, Fair Value | 62,316 | 45,965
Unrealized Loss Position, Unrealized Losses [Abstract] |  |
Less than 12 months Unrealized Losses | (439) | (36)
12 months or longer Unrealized Losses | (59) | (254)
Total Unrealized Losses | $ (498) | $ (290)
Unrealized Loss Position, Number of Positions [Abstract] |  |
Less Than 12 Months, Number of Positions | Position | 28 | 10
12 Months or Longer, Number of Positions | Position | 17 | 31
Total, Number of Positions | Position | 45 | 41
Mortgage-backed Securities, Issued by US Government-Sponsored Enterprises [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Amortized cost | $ 333,292 | $ 339,190
Unrealized gains | 5,914 | 7,597
Unrealized losses | (439) | (224)
Estimated fair value | 338,767 | 346,563
Mortgage-backed Securities, Issued by US Government Securities [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Amortized cost | 15,325 | 17,367
Unrealized gains | 796 | 863
Unrealized losses | (59) | (66)
Estimated fair value | 16,062 | 18,164
Collateralized Mortgage Obligations [Member] |  |
Unrealized Loss Position, Fair Value [Abstract] |  |
Less Than 12 Months, Fair Value | 87,849 | 57,682
12 Months or Longer, Fair Value | 5,452 | 6,598
Total, Fair Value | 93,301 | 64,280
Unrealized Loss Position, Unrealized Losses [Abstract] |  |
Less than 12 months Unrealized Losses | (531) | (196)
12 months or longer Unrealized Losses | (38) | (74)
Total Unrealized Losses | $ (569) | $ (270)
Unrealized Loss Position, Number of Positions [Abstract] |  |
Less Than 12 Months, Number of Positions | Position | 9 | 8
12 Months or Longer, Number of Positions | Position | 4 | 4
Total, Number of Positions | Position | 13 | 12
Government-sponsored Enterprises [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Amortized cost | $ 285,733 | $ 199,837
Unrealized gains | 1,966 | 1,828
Unrealized losses | (535) | (234)
Estimated fair value | 287,164 | 201,431
U.S. Government Agency Securities [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Amortized cost | 33,965 | 40,237
Unrealized gains | 428 | 497
Unrealized losses | (34) | (36)
Estimated fair value | 34,359 | 40,698
Other Securities [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Amortized cost | 12,872 | 12,818
Unrealized gains | 2,870 | 3,054
Unrealized losses | (142) | (152)
Estimated fair value | 15,600 | 15,720
Unrealized Loss Position, Fair Value [Abstract] |  |
Less Than 12 Months, Fair Value | 0 | 0
12 Months or Longer, Fair Value | 3,211 | 3,201
Total, Fair Value | 3,211 | 3,201
Unrealized Loss Position, Unrealized Losses [Abstract] |  |
Less than 12 months Unrealized Losses | 0 | 0
12 months or longer Unrealized Losses | (142) | (152)
Total Unrealized Losses | $ (142) | $ (152)
Unrealized Loss Position, Number of Positions [Abstract] |  |
Less Than 12 Months, Number of Positions | Position | 0 | 0
12 Months or Longer, Number of Positions | Position | 2 | 2
Total, Number of Positions | Position | 2 | 2
Mortgage-Backed [Member] |  |
Unrealized Loss Position, Fair Value [Abstract] |  |
Less Than 12 Months, Fair Value | $ 9,907 |
12 Months or Longer, Fair Value | 0 |
Total, Fair Value | 9,907 |
Unrealized Loss Position, Unrealized Losses [Abstract] |  |
Less Than 12 Months, Unrealized Losses | (142) |
12 Months or Longer, Unrealized Losses | 0 |
Total, Unrealized Losses | $ (142) |
Unrealized Loss Position, Number of Positions [Abstract] |  |
Held-to-maturity, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year | Position | 1 |
Held-to-maturity, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater Than or Equal to One Year | Position | 0 |
Total, Number of Positions | Position | 1 |
Mortgage-Backed [Member] | Government-sponsored Enterprises [Member] |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Amortized cost | $ 10,049 | $ 755
Unrealized gains | 0 | 113
Unrealized losses | (142) | 0
Estimated fair value | 9,907 | 868
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount [Abstract] |  |
Amortized cost | 10,049 | 755
Held-to-maturity Securities, Debt Maturities, Fair Value [Abstract] |  |
Total, Fair Value | 9,907 | 868
Mortgage-Backed [Member] | U.S. Government Agency Securities [Member] |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Amortized cost | 695 |
Unrealized gains | 118 |
Unrealized losses | 0 |
Estimated fair value | 813 |
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount [Abstract] |  |
Amortized cost | 695 |
Held-to-maturity Securities, Debt Maturities, Fair Value [Abstract] |  |
Total, Fair Value | 813 |
State & Municipal [Member] |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Amortized cost | 148,058 | 135,978
Unrealized gains | 466 | 674
Unrealized losses | (442) | (123)
Estimated fair value | 148,082 | 136,529
Unrealized Loss Position, Fair Value [Abstract] |  |
Less Than 12 Months, Fair Value | 43,095 | 43,514
12 Months or Longer, Fair Value | 0 | 1,619
Total, Fair Value | 43,095 | 45,133
Unrealized Loss Position, Unrealized Losses [Abstract] |  |
Less Than 12 Months, Unrealized Losses | (442) | (116)
12 Months or Longer, Unrealized Losses | 0 | (7)
Total, Unrealized Losses | $ (442) | $ (123)
Unrealized Loss Position, Number of Positions [Abstract] |  |
Held-to-maturity, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year | Position | 89 | 110
Held-to-maturity, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater Than or Equal to One Year | Position | 0 | 6
Total, Number of Positions | Position | 89 | 116
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount [Abstract] |  |
Amortized cost | $ 148,058 | $ 135,978
Held-to-maturity Securities, Debt Maturities, Fair Value [Abstract] |  |
Total, Fair Value | 148,082 | 136,529
Collateralized Mortgage Obligations [Member] |  |
Unrealized Loss Position, Fair Value [Abstract] |  |
Less Than 12 Months, Fair Value | 76,008 | 26,052
12 Months or Longer, Fair Value | 44,136 | 46,415
Total, Fair Value | 120,144 | 72,467
Unrealized Loss Position, Unrealized Losses [Abstract] |  |
Less Than 12 Months, Unrealized Losses | (306) | (49)
12 Months or Longer, Unrealized Losses | (1,520) | (1,916)
Total, Unrealized Losses | $ (1,826) | $ (1,965)
Unrealized Loss Position, Number of Positions [Abstract] |  |
Held-to-maturity, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year | Position | 8 | 2
Held-to-maturity, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater Than or Equal to One Year | Position | 4 | 4
Total, Number of Positions | Position | 12 | 6
Collateralized Mortgage Obligations [Member] | Government-sponsored Enterprises [Member] |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Amortized cost | $ 295,510 | $ 317,628
Unrealized gains | 1,769 | 1,934
Unrealized losses | (1,826) | (1,965)
Estimated fair value | 295,453 | 317,597
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount [Abstract] |  |
Amortized cost | 295,510 | 317,628
Held-to-maturity Securities, Debt Maturities, Fair Value [Abstract] |  |
Total, Fair Value | $ 295,453 | $ 317,597

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