Investments (Details 1) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2016 USD ($) Number	Dec. 31, 2015 USD ($) Number
Schedule of Available-for-sale Securities [Line Items]
No. of securities | Number	89	212
Fair value, Less than 12 months	$ 31,245	$ 106,304
Unrealized losses, Less than 12 months	(142)	(877)
Fair value, 12 months or longer	11,499	12,101
Unrealized losses, 12 months or longer	(107)	(198)
Total, Fair value	42,744	118,405
Total, Unrealized losses	$ (249)	$ (1,075)
U. S. treasury securities [Member]
Schedule of Available-for-sale Securities [Line Items]
No. of securities | Number		2
Fair value, Less than 12 months		$ 3,542
Unrealized losses, Less than 12 months		(1)
Fair value, 12 months or longer		0
Unrealized losses, 12 months or longer		0
Total, Fair value		3,542
Total, Unrealized losses		$ (1)
U.S. federal agency obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
No. of securities | Number	4	18
Fair value, Less than 12 months	$ 5,489	$ 23,015
Unrealized losses, Less than 12 months	(9)	(163)
Fair value, 12 months or longer	3,189	1,976
Unrealized losses, 12 months or longer	(17)	(24)
Total, Fair value	8,678	24,991
Total, Unrealized losses	$ (26)	$ (187)
Municipal obligations, tax exempt [Member]
Schedule of Available-for-sale Securities [Line Items]
No. of securities | Number	45	47
Fair value, Less than 12 months	$ 14,384	$ 11,328
Unrealized losses, Less than 12 months	(91)	(53)
Fair value, 12 months or longer	923	2,132
Unrealized losses, 12 months or longer	(5)	(18)
Total, Fair value	15,307	13,460
Total, Unrealized losses	$ (96)	$ (71)
Municipal obligations, taxable [Member]
Schedule of Available-for-sale Securities [Line Items]
No. of securities | Number	20	105
Fair value, Less than 12 months	$ 6,077	$ 38,605
Unrealized losses, Less than 12 months	(29)	(494)
Fair value, 12 months or longer	4,690	5,068
Unrealized losses, 12 months or longer	(51)	(87)
Total, Fair value	10,767	43,673
Total, Unrealized losses	$ (80)	$ (581)
Agency mortgage-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
No. of securities | Number	20	40
Fair value, Less than 12 months	$ 5,295	$ 29,814
Unrealized losses, Less than 12 months	(13)	(166)
Fair value, 12 months or longer	2,697	2,925
Unrealized losses, 12 months or longer	(34)	(69)
Total, Fair value	7,992	32,739
Total, Unrealized losses	$ (47)	$ (235)