Securities - Gross Unrealized Losses and Fair Value by Investment Category (Details) $ in Thousands	Mar. 31, 2020 USD ($) security	Dec. 31, 2019 USD ($) security
Available for Sale:
Number of positions, Less than 12 Months \| security	40	79
Fair Value, Less than 12 Months	$ 80,677	$ 331,023
Unrealized Losses, Less than 12 Months	$ (5,782)	$ (2,394)
Number of positions, 12 Months or More \| security	2	22
Fair value, 12 Months or More	$ 1,176	$ 33,700
Unrealized Losses, 12 Months or More	$ (2)	$ (2,484)
Number of positions \| security	42	101
Fair Value	$ 81,853	$ 364,723
Unrealized Losses	$ (5,784)	$ (4,878)
Obligations of other U.S. Government agencies and corporations
Available for Sale:
Number of positions, Less than 12 Months \| security		0
Fair Value, Less than 12 Months		$ 0
Unrealized Losses, Less than 12 Months		$ 0
Number of positions, 12 Months or More \| security		1
Fair value, 12 Months or More		$ 1,008
Unrealized Losses, 12 Months or More		$ (3)
Number of positions \| security		1
Fair Value		$ 1,008
Unrealized Losses		$ (3)
Obligations of states and political subdivisions
Available for Sale:
Number of positions, Less than 12 Months \| security	29	26
Fair Value, Less than 12 Months	$ 47,604	$ 33,902
Unrealized Losses, Less than 12 Months	$ (1,872)	$ (365)
Number of positions, 12 Months or More \| security	0	0
Fair value, 12 Months or More	$ 0	$ 0
Unrealized Losses, 12 Months or More	$ 0	$ 0
Number of positions \| security	29	26
Fair Value	$ 47,604	$ 33,902
Unrealized Losses	$ (1,872)	$ (365)
Trust preferred securities
Available for Sale:
Number of positions, Less than 12 Months \| security	2	0
Fair Value, Less than 12 Months	$ 8,604	$ 0
Unrealized Losses, Less than 12 Months	$ (3,487)	$ 0
Number of positions, 12 Months or More \| security	0	2
Fair value, 12 Months or More	$ 0	$ 9,986
Unrealized Losses, 12 Months or More	$ 0	$ (2,167)
Number of positions \| security	2	2
Fair Value	$ 8,604	$ 9,986
Unrealized Losses	$ (3,487)	$ (2,167)
Other debt securities
Available for Sale:
Number of positions, Less than 12 Months \| security	5	3
Fair Value, Less than 12 Months	$ 11,987	$ 8,737
Unrealized Losses, Less than 12 Months	$ (245)	$ (131)
Number of positions, 12 Months or More \| security	0	1
Fair value, 12 Months or More	$ 0	$ 741
Unrealized Losses, 12 Months or More	$ 0	$ (1)
Number of positions \| security	5	4
Fair Value	$ 11,987	$ 9,478
Unrealized Losses	$ (245)	$ (132)
Government agency mortgage backed securities \| Residential mortgage backed securities:
Available for Sale:
Number of positions, Less than 12 Months \| security	1	37
Fair Value, Less than 12 Months	$ 106	$ 233,179
Unrealized Losses, Less than 12 Months	$ 0	$ (1,504)
Number of positions, 12 Months or More \| security	0	16
Fair value, 12 Months or More	$ 0	$ 20,775
Unrealized Losses, 12 Months or More	$ 0	$ (312)
Number of positions \| security	1	53
Fair Value	$ 106	$ 253,954
Unrealized Losses	$ 0	$ (1,816)
Government agency mortgage backed securities \| Commercial mortgage backed securities:
Available for Sale:
Number of positions, Less than 12 Months \| security	0	1
Fair Value, Less than 12 Months	$ 0	$ 4,976
Unrealized Losses, Less than 12 Months	$ 0	$ (23)
Number of positions, 12 Months or More \| security	2	2
Fair value, 12 Months or More	$ 1,176	$ 1,190
Unrealized Losses, 12 Months or More	$ (2)	$ (1)
Number of positions \| security	2	3
Fair Value	$ 1,176	$ 6,166
Unrealized Losses	$ (2)	$ (24)
Government agency collateralized mortgage obligations \| Residential mortgage backed securities:
Available for Sale:
Number of positions, Less than 12 Months \| security	0	11
Fair Value, Less than 12 Months	$ 0	$ 45,319
Unrealized Losses, Less than 12 Months	$ 0	$ (262)
Number of positions, 12 Months or More \| security	0	0
Fair value, 12 Months or More	$ 0	$ 0
Unrealized Losses, 12 Months or More	$ 0	$ 0
Number of positions \| security	0	11
Fair Value	$ 0	$ 45,319
Unrealized Losses	$ 0	$ (262)
Government agency collateralized mortgage obligations \| Commercial mortgage backed securities:
Available for Sale:
Number of positions, Less than 12 Months \| security	3	1
Fair Value, Less than 12 Months	$ 12,376	$ 4,910
Unrealized Losses, Less than 12 Months	$ (178)	$ (109)
Number of positions, 12 Months or More \| security	0	0
Fair value, 12 Months or More	$ 0	$ 0
Unrealized Losses, 12 Months or More	$ 0	$ 0
Number of positions \| security	3	1
Fair Value	$ 12,376	$ 4,910
Unrealized Losses	$ (178)	$ (109)

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for 12 months or longer, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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Number of investments in debt securities measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for 12 months or longer, without an allowance for credit loss. Includes beneficial interest in securitized financial asset.

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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