CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Consolidated Statements Of Comprehensive Income
Net Income	$ 5,571	$ 7,614	$ 7,450	$ 6,945	$ 6,050	$ 7,799	$ 7,474	$ 7,602	$ 27,581	$ 28,925	$ 27,808
Other Comprehensive Income (Loss), net of tax: Unrealized Gain (Loss) on investments, net of tax benefit of $408 in 2016, net of tax expense of $283 in 2015 and net of tax benefit of $131 in 2014									(757)	528	(245)
Comprehensive Income									$ 26,824	$ 29,453	$ 27,563