Available-for-Sale Securities - Amortized Cost, Gross Unrealized Gains and Losses, and Fair Value of Available-for-Sale Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	$ 29,234	$ 52,942
Gross Unrealized Gains	38	132
Gross Unrealized Losses	(375)	(384)
Fair Value	28,897	52,690
U.S. Government and Federal Agencies
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	24,911	41,906
Gross Unrealized Losses	(359)	(347)
Fair Value	24,552	41,559
Certificates of Deposit
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost		500
Fair Value		500
FHLMC Certificates
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost		192
Gross Unrealized Gains		24
Fair Value		216
FNMA Certificates
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	1,118	3,600
Gross Unrealized Gains		11
Gross Unrealized Losses	(15)	(5)
Fair Value	1,103	3,606
GNMA Certificates
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	3,205	6,744
Gross Unrealized Gains	38	97
Gross Unrealized Losses	(1)	(32)
Fair Value	$ 3,242	$ 6,809

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 25
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=75030427&loc=d3e22054-111558

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
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-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27232-111563

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=82896770&loc=d3e26610-111562

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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-Section 50
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This item represents the cost of debt and equity 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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.2)
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