Condensed Consolidated Statements Of Comprehensive Income (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement of Comprehensive Income [Abstract]
Unrealized gain on investments, net of tax expense of $9 and $49 in 2018 and $49 and $23 in 2017	$ 9	$ 49	$ 49	$ 23
Unrealized gain (loss), net of tax expense (benefit) of $2,161 and $1,784 in 2018 and $(2,287) and $(3,199) in 2017	2,161	(2,287)	1,784	(3,199)
Reclassification adjustment for losses (gains) included in net income, net of tax benefit (expense) of $379 and $629 in 2018 and $(280) and $(681) in 2017	$ 379	$ (280)	$ 629	$ (681)