Consolidated Statements Of Comprehensive Income (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Consolidated Statements Of Comprehensive Income [Abstract]
Unrealized gain (loss) on investments, tax expense (benefit)	$ 113	$ (93)	$ (63)
Unrealized gain, tax expense	2,174	3,736	4,073
Reclassification adjustment for gains included in net income, tax expense	$ 949	$ 5,853	$ 756