Investments (Tables)

12 Months Ended

Dec. 31, 2020

Investments, Debt and Equity Securities [Abstract]

Schedule of amortized cost and fair value of securities available-for-sale

The amortized cost and fair value of securities available for sale are as follows:

	December 31, 2020
	Amortized Cost		Allowance for credit losses(1)		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Available for sale:
Mortgage-backed securities	$	308,913	$	—	$	6,095	$	(134)	$	314,874
Utah Housing Corporation bonds	12,357		—		210		—		12,567
U.S. government-sponsored enterprises and Treasuries	1,596,890		—		3,395		—		1,600,285
Other securities	68,797		—		462		(351)		68,908
Total	$	1,986,957	$	—	$	10,162	$	(485)	$	1,996,634
	December 31, 2019
	Amortized Cost		Allowance for credit losses(1)		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Available for sale:
Mortgage-backed securities	$	215,888	$	—	$	1,895	$	(658)	$	217,125
Utah Housing Corporation bonds	19,474		—		145		(83)		19,536
U.S. government-sponsored enterprises	250,394		—		635		(21)		251,008
Total	$	485,756	$	—	$	2,675	$	(762)	$	487,669

Available-for-sale securities, continuous unrealized loss position, fair value

The following table summarizes the amount of gross unrealized losses for our available-for-sale securities and the estimated fair value for securities having gross unrealized loss positions, categorized by length of time the securities have been in an unrealized loss position:

	Less than 12 months				12 months or more				Total
	Gross Unrealized Losses		Estimated Fair Value		Gross Unrealized Losses		Estimated Fair Value		Gross Unrealized Losses		Estimated Fair Value
As of December 31, 2020:
Mortgage-backed securities	$	(134)	$	46,011	$	—	$	—	$	(134)	$	46,011
Utah Housing Corporation bonds	—		—		—		—		—		—
U.S. government-sponsored enterprises and Treasuries	—		—		—		—		—		—
Other securities	(351)		30,441		—		—		(351)		30,441
Total	$	(485)	$	76,452	$	—	$	—	$	(485)	$	76,452
As of December 31, 2019:
Mortgage-backed securities	$	(218)	$	25,624	$	(440)	$	42,448	$	(658)	$	68,072
Utah Housing Corporation bonds	—		—		(83)		11,097		(83)		11,097
U.S. government-sponsored enterprises	(21)		14,977		—		—		(21)		14,977
Total	$	(239)	$	40,601	$	(523)	$	53,545	$	(762)	$	94,146

Amortized cost and fair value of securities by contractual maturities

As of December 31, 2020, the amortized cost and fair value of securities, by contractual maturities, are summarized below. Contractual maturities versus actual maturities may differ due to the effect of prepayments.

Year of Maturity	Amortized Cost		Estimated Fair Value
2021	$	454,193	$	455,185
2022	978,017		979,802
2023	164,680		165,299
2038	170		195
2039	2,032		2,249
2042	4,767		4,769
2043	8,745		9,153
2044	11,586		12,139
2045	9,739		10,133
2046	15,292		15,748
2047	25,056		25,574
2048	6,466		6,743
2049	44,711		46,681
2050	192,706		194,056
2054	68,797		68,908
Total	$	1,986,957	$	1,996,634