Investments - Amortized Cost and Fair Value of Securities Available for Sale (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 454,603	$ 182,325
Gross Unrealized Gains	2,429	178
Gross Unrealized Losses	(1,064)	(6,258)
Available-for-sale investments	455,968	176,245
Mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	219,531	159,937
Gross Unrealized Gains	1,807	155
Gross Unrealized Losses	(723)	(5,517)
Available-for-sale investments	220,615	154,575
Utah Housing Corporation bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	19,474	22,388
Gross Unrealized Gains	149	23
Gross Unrealized Losses	(261)	(741)
Available-for-sale investments	19,362	$ 21,670
U.S. government-sponsored enterprises
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	215,598
Gross Unrealized Gains	473
Gross Unrealized Losses	(80)
Available-for-sale investments	$ 215,991

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on 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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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

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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).

+ References

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-Publisher FASB
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-Section 50
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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).

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