Investment in Available-for-Sale Securities (Details) - USD ($)	3 Months Ended	12 Months Ended
Mar. 31, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Cost	$ 1,606,380	$ 1,770,889
Available-for-sale Securities, Unrealized Gains	26,738	21,141
Available-for-sale Securities, Unrealized Losses	(10,962)	(15,845)
Available-for-sale Securities, Fair Value	1,622,156	1,776,185
U.S. federal agency securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Cost	4,852	4,830
Available-for-sale Securities, Unrealized Gains	76	55
Available-for-sale Securities, Unrealized Losses	0	0
Available-for-sale Securities, Fair Value	4,928	4,885
Municipal securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Cost	435,190	492,237
Available-for-sale Securities, Unrealized Gains	1,762	789
Available-for-sale Securities, Unrealized Losses	(176)	(980)
Available-for-sale Securities, Fair Value	436,776	492,046
Certificates of deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Cost	1,149,290	1,256,649
Available-for-sale Securities, Unrealized Gains	24,693	20,182
Available-for-sale Securities, Unrealized Losses	(10,786)	(14,865)
Available-for-sale Securities, Fair Value	1,163,197	1,261,966
Corporate debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Cost	17,048	17,173
Available-for-sale Securities, Unrealized Gains	207	115
Available-for-sale Securities, Unrealized Losses	0	0
Available-for-sale Securities, Fair Value	$ 17,255	$ 17,288

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=51813488&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
-Subparagraph (aa)
-URI http://asc.fasb.org/extlink&oid=27724398&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=49167202&loc=d3e26610-111562

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+ 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)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Amount of unrealized gain before deducting unrealized loss on investments in debt and equity securities classified as available-for-sale securities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27161-111563

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Amount of unrealized loss before deducting unrealized gain on investments in available-for-sale securities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27161-111563

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