Investments - Amortized Cost and Fair Value of Securities Available for Sale (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Available for sale:
Amortized Cost	$ 247,607	$ 211,406
Gross Unrealized Gains	650	929
Gross Unrealized Losses	(4,169)	(3,732)
Mortgage-backed securities	244,088	208,603
Mortgage-backed securities
Available for sale:
Amortized Cost	227,607	196,406
Gross Unrealized Gains	650	929
Gross Unrealized Losses	(3,210)	(3,042)
Mortgage-backed securities	225,047	194,293
Utah Housing Corporation bonds
Available for sale:
Amortized Cost	20,000	15,000
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(959)	(690)
Mortgage-backed securities	$ 19,041	$ 14,310

Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt securities classified as available-for-sale.

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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt securities classified as available-for-sale.

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This item represents the cost of debt securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

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-Publisher FASB
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Amount of debt securities categorized neither as held-to-maturity nor trading.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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