Consolidated Statements of Stockholders' Equity (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Tax benefits exercise stock options	$ 407	$ 1,056	$ 2,984
Common Stock [Member]
Tax benefits exercise stock options	407	1,056	2,984
Additional Paid-in Capital [Member]
Tax benefits exercise stock options	$ 407	$ 1,056	$ 2,984