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Number Of Government Sponsored Securities

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Amount of affordable housing tax credits and other tax benefits recognized.

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Amount of investment in qualified affordable housing projects.

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Amount of amortization expense of investment in qualified affordable housing projects.

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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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Investments - Additional Information (Details) $ in Thousands	3 Months Ended		12 Months Ended
	Sep. 30, 2019 USD ($)	Jun. 30, 2018 USD ($) security	Dec. 31, 2019 USD ($) security	Dec. 31, 2018 USD ($) security	Dec. 31, 2017 USD ($)
Investment Holdings [Line Items]
Amortized Cost			$ 485,756	$ 182,325
Par value of mortgage-backed securities pledged to FRB			252,000	147,000
Gain on equity securities investment	$ 8,000
Non-marketable securities investment			26,000	8,000
Low income housing tax credit investments			6,000	4,000	$ 1,000
Amount of amortization reported in income tax expense			4,000	4,000	$ 1,000
Total carrying value of LIHTC investments			58,000	48,000
Liability for unfunded commitments			29,000	37,000
Mortgage-backed securities
Investment Holdings [Line Items]
Amortized Cost			$ 215,888	$ 159,937
Number of mortgage-backed securities sold \| security		9
Proceeds from sale of securities		$ 41,000
Recognized loss from sale of securities		$ 2,000
Number of mortgage-backed securities with unrealized losses \| security			33	74
Number of mortgage-backed securities \| security			107	86
Utah Housing Corporation bonds
Investment Holdings [Line Items]
Amortized Cost			$ 19,474	$ 22,388
Utah Housing Corporation bonds \| Aa3 Rating
Investment Holdings [Line Items]
Amortized Cost			19,000	$ 22,000
U.S. government-sponsored enterprises
Investment Holdings [Line Items]
Amortized Cost			$ 250,394
Number of government sponsored securities \| security			14
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions \| security			1
Government National Mortgage Association Certificates and Obligations (GNMA) \| Mortgage-backed securities
Investment Holdings [Line Items]
Amortized Cost			$ 54,000
Number of mortgage-backed securities with unrealized losses \| security			18	34
Federal National Mortgage Association Certificates and Obligations (FNMA) \| Mortgage-backed securities
Investment Holdings [Line Items]
Amortized Cost			$ 106,000
Federal Home Loan Mortgage Corporation Certificates and Obligations (FHLMC) \| Mortgage-backed securities
Investment Holdings [Line Items]
Amortized Cost			$ 56,000