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Securities - General Disclosures (Details) - USD ($) $ in Thousands | 3 Months Ended |
--- | --- | ---
Mar. 31, 2019 | Dec. 31, 2018
Securities |  |
Equity securities consisting of common stock and money market mutual funds, fair value | $ 6,378 | $ 6,169
Unrealized losses recorded | (216) |
Available for sale |  |
Amortized Cost | 1,916,060 | 707,213
Gross Unrealized Gains | 10,029 | 798
Gross Unrealized Losses | (7,794) | (10,326)
Fair Value | 1,918,295 | 697,685
Held to maturity |  |
Amortized Cost | 15,846 | 608,660
Gross Unrealized Gains |  | 1,827
Gross Unrealized Losses |  | (7,127)
Fair Value | 15,975 | 603,360
Available for sale, Amortized Cost |  |
Due in one year or less | 166,786 |
Due after one year through five years | 517,731 |
Due after five years through ten years | 276,057 |
Due after ten years | 955,486 |
Amortized Cost | 1,916,060 | 707,213
Available for sale, Fair Value |  |
Due in one year or less | 166,734 |
Due after one year through five years | 519,968 |
Due after five years through ten years | 277,308 |
Due after ten years | 954,285 |
Fair Value | 1,918,295 | 697,685
Held to maturity, Amortized Cost |  |
Due in one year or less | 1,914 |
Due after one year through five years | 12,807 |
Due after five years through ten years | 1,125 |
Amortized Cost | 15,846 | 608,660
Held to maturity, Fair Value |  |
Due in one year or less | 1,913 |
Due after one year through five years | 12,909 |
Due after five years through ten years | 1,153 |
Fair Value | 15,975 | 603,360
Realized gains and losses related to sales and calls of securities AFS |  |
Gross security gains | 184 |
Security gains (losses), net | 184 |
Available for sale, Fair Value |  |
Continuous unrealized losses existing for less than 12 months, gross | 43,331 | 190,737
Continuous unrealized losses existing for greater than 12 months, gross | 711,477 | 417,336
Total, gross | 754,808 | 608,073
Available for sale, Unrealized Losses |  |
Continuous unrealized losses existing for less than 12 months, gross | (57) | (1,231)
Continuous unrealized losses existing greater than 12 months, gross | (7,737) | (9,095)
Total, gross | $ (7,794) | (10,326)
Held to maturity, Fair Value |  |
Continuous unrealized losses existing for less than 12 months, gross |  | 98,669
Continuous unrealized losses existing for greater than 12 months, gross |  | 299,707
Total, gross |  | 398,376
Held to maturity, Unrealized Losses |  |
Continuous unrealized losses existing for less than 12 months, gross |  | (1,219)
Continuous unrealized losses existing for greater than 12 months, gross |  | (5,908)
Total, gross |  | (7,127)
Security portfolio evaluated for other-than-temporary impairment | 1,354 |
Number of securities in unrealized loss position | 366 |
Securities in unrealized loss position as a percentage of aggregate carrying value of investments | 1.02% |
Collateral |  |
Realized gains and losses related to sales and calls of securities AFS |  |
Carrying amount of investment securities pledged as collateral | $ 564,000 | 498,300
U.S. Treasury securities |  |
Available for sale |  |
Amortized Cost | 64,506 | 25,824
Gross Unrealized Gains | 76 | 1
Gross Unrealized Losses | (273) | (414)
Fair Value | 64,309 | 25,411
Available for sale, Amortized Cost |  |
Amortized Cost | 64,506 | 25,824
Available for sale, Fair Value |  |
Fair Value | 64,309 | 25,411
Available for sale, Fair Value |  |
Continuous unrealized losses existing for less than 12 months, gross | 7,484 | 995
Continuous unrealized losses existing for greater than 12 months, gross | 24,505 | 24,343
Total, gross | 31,989 | 25,338
Available for sale, Unrealized Losses |  |
Continuous unrealized losses existing for less than 12 months, gross | (2) | (4)
Continuous unrealized losses existing greater than 12 months, gross | (271) | (410)
Total, gross | (273) | (414)
Obligations of U.S. government corporations and agencies |  |
Available for sale |  |
Amortized Cost | 323,686 | 53,096
Gross Unrealized Gains | 2,122 | 7
Gross Unrealized Losses | (388) | (761)
Fair Value | 325,420 | 52,342
Available for sale, Amortized Cost |  |
Amortized Cost | 323,686 | 53,096
Available for sale, Fair Value |  |
Fair Value | 325,420 | 52,342
Available for sale, Fair Value |  |
Continuous unrealized losses existing for less than 12 months, gross | 750 | 749
Continuous unrealized losses existing for greater than 12 months, gross | 50,966 | 50,744
Total, gross | 51,716 | 51,493
Available for sale, Unrealized Losses |  |
Continuous unrealized losses existing for less than 12 months, gross | (2) | (3)
Continuous unrealized losses existing greater than 12 months, gross | (386) | (758)
Total, gross | (388) | (761)
Obligations of states and political subdivisions |  |
Available for sale |  |
Amortized Cost | 281,473 | 171,131
Gross Unrealized Gains | 2,357 | 484
Gross Unrealized Losses | (352) | (1,571)
Fair Value | 283,478 | 170,044
Held to maturity |  |
Amortized Cost | 15,846 | 33,947
Gross Unrealized Gains | 132 | 68
Gross Unrealized Losses | (3) | (87)
Fair Value | 15,975 | 33,928
Available for sale, Amortized Cost |  |
Amortized Cost | 281,473 | 171,131
Available for sale, Fair Value |  |
Fair Value | 283,478 | 170,044
Held to maturity, Amortized Cost |  |
Amortized Cost | 15,846 | 33,947
Held to maturity, Fair Value |  |
Fair Value | 15,975 | 33,928
Available for sale, Fair Value |  |
Continuous unrealized losses existing for less than 12 months, gross | 11,453 | 49,893
Continuous unrealized losses existing for greater than 12 months, gross | 63,959 | 77,651
Total, gross | 75,412 | 127,544
Available for sale, Unrealized Losses |  |
Continuous unrealized losses existing for less than 12 months, gross | (28) | (460)
Continuous unrealized losses existing greater than 12 months, gross | (324) | (1,111)
Total, gross | (352) | (1,571)
Held to maturity, Fair Value |  |
Continuous unrealized losses existing for less than 12 months, gross |  | 9,531
Continuous unrealized losses existing for greater than 12 months, gross | 2,301 | 9,538
Total, gross | 2,301 | 19,069
Held to maturity, Unrealized Losses |  |
Continuous unrealized losses existing for less than 12 months, gross |  | (33)
Continuous unrealized losses existing for greater than 12 months, gross | (3) | (54)
Total, gross | (3) | (87)
Commercial mortgage-backed securities |  |
Available for sale |  |
Amortized Cost | 55,926 | 2,003
Gross Unrealized Gains | 29 |
Gross Unrealized Losses | (393) | (61)
Fair Value | 55,562 | 1,942
Held to maturity |  |
Amortized Cost |  | 59,054
Gross Unrealized Gains |  | 11
Gross Unrealized Losses |  | (1,003)
Fair Value |  | 58,062
Available for sale, Amortized Cost |  |
Amortized Cost | 55,926 | 2,003
Available for sale, Fair Value |  |
Fair Value | 55,562 | 1,942
Held to maturity, Amortized Cost |  |
Amortized Cost |  | 59,054
Held to maturity, Fair Value |  |
Fair Value |  | 58,062
Available for sale, Fair Value |  |
Continuous unrealized losses existing for greater than 12 months, gross | 430 | 1,942
Total, gross | 430 | 1,942
Available for sale, Unrealized Losses |  |
Continuous unrealized losses existing greater than 12 months, gross | (393) | (61)
Total, gross | (393) | (61)
Held to maturity, Fair Value |  |
Continuous unrealized losses existing for less than 12 months, gross |  | 12,067
Continuous unrealized losses existing for greater than 12 months, gross |  | 45,041
Total, gross |  | 57,108
Held to maturity, Unrealized Losses |  |
Continuous unrealized losses existing for less than 12 months, gross |  | (212)
Continuous unrealized losses existing for greater than 12 months, gross |  | (791)
Total, gross |  | (1,003)
Residential mortgage-backed securities |  |
Available for sale |  |
Amortized Cost | 1,051,556 | 322,646
Gross Unrealized Gains | 4,512 | 245
Gross Unrealized Losses | (6,307) | (7,143)
Fair Value | 1,049,761 | 315,748
Held to maturity |  |
Amortized Cost |  | 515,659
Gross Unrealized Gains |  | 1,748
Gross Unrealized Losses |  | (6,037)
Fair Value |  | 511,370
Available for sale, Amortized Cost |  |
Amortized Cost | 1,051,556 | 322,646
Available for sale, Fair Value |  |
Fair Value | 1,049,761 | 315,748
Held to maturity, Amortized Cost |  |
Amortized Cost |  | 515,659
Held to maturity, Fair Value |  |
Fair Value |  | 511,370
Available for sale, Fair Value |  |
Continuous unrealized losses existing for less than 12 months, gross | 16,083 | 48,387
Continuous unrealized losses existing for greater than 12 months, gross | 551,248 | 247,573
Total, gross | 567,331 | 295,960
Available for sale, Unrealized Losses |  |
Continuous unrealized losses existing for less than 12 months, gross | (9) | (496)
Continuous unrealized losses existing greater than 12 months, gross | (6,298) | (6,647)
Total, gross | (6,307) | (7,143)
Held to maturity, Fair Value |  |
Continuous unrealized losses existing for less than 12 months, gross |  | 77,071
Continuous unrealized losses existing for greater than 12 months, gross |  | 245,128
Total, gross |  | 322,199
Held to maturity, Unrealized Losses |  |
Continuous unrealized losses existing for less than 12 months, gross |  | (974)
Continuous unrealized losses existing for greater than 12 months, gross |  | (5,063)
Total, gross |  | (6,037)
Corporate debt securities |  |
Available for sale |  |
Amortized Cost | 138,913 | 132,513
Gross Unrealized Gains | 933 | 61
Gross Unrealized Losses | (81) | (376)
Fair Value | 139,765 | 132,198
Available for sale, Amortized Cost |  |
Amortized Cost | 138,913 | 132,513
Available for sale, Fair Value |  |
Fair Value | 139,765 | 132,198
Available for sale, Fair Value |  |
Continuous unrealized losses existing for less than 12 months, gross | 7,561 | 90,713
Continuous unrealized losses existing for greater than 12 months, gross | 20,369 | 15,083
Total, gross | 27,930 | 105,796
Available for sale, Unrealized Losses |  |
Continuous unrealized losses existing for less than 12 months, gross | (16) | (268)
Continuous unrealized losses existing greater than 12 months, gross | (65) | (108)
Total, gross | (81) | $ (376)
Accounting Standards Update 2017-12 |  |
Realized gains and losses related to sales and calls of securities AFS |  |
Transferred securities from held to maturity to available-for-sale | 573,600 |
Unrealized loss related to transfer of securities from held to maturity to AFS | $ 4,800 |

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