Securities - Contractual Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Amortized Cost
Due within one year	$ 9,438
Due after one year through five years	45,943
Due after five years through ten years	74,337
Due after ten years	215,924
Amortized Cost	1,301,973	$ 1,276,871
Fair Value
Due within one year	9,520
Due after one year through five years	48,017
Due after five years through ten years	78,271
Due after ten years	221,836
Fair Value	1,343,457	1,290,613
Residential mortgage backed securities \| Government agency mortgage backed securities
Amortized Cost
Without single maturity date, amortized cost	581,105
Amortized Cost	581,105	708,970
Fair Value
Without single maturity date, fair value	602,646
Fair Value	602,646	716,105
Residential mortgage backed securities \| Government agency collateralized mortgage obligations
Amortized Cost
Without single maturity date, amortized cost	218,373
Amortized Cost	218,373	172,178
Fair Value
Without single maturity date, fair value	220,268
Fair Value	220,268	173,238
Commercial mortgage backed securities \| Government agency mortgage backed securities
Amortized Cost
Without single maturity date, amortized cost	29,053
Amortized Cost	29,053	30,372
Fair Value
Without single maturity date, fair value	30,287
Fair Value	30,287	31,007
Commercial mortgage backed securities \| Government agency collateralized mortgage obligations
Amortized Cost
Without single maturity date, amortized cost	99,377
Amortized Cost	99,377	76,456
Fair Value
Without single maturity date, fair value	102,348
Fair Value	102,348	77,751
Other debt securities
Amortized Cost
Without single maturity date, amortized cost	28,423
Amortized Cost	62,771	55,364
Fair Value
Without single maturity date, fair value	30,264
Fair Value	$ 65,607	$ 56,365

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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