Consolidated Statements of Stockholders' Equity (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017
Statement of Stockholders' Equity [Abstract]
Dividends (in dollars per share)	$ 0.38	$ 0.47	$ 0.42
Income tax benefit of shares and options issued under stock plans	$ 2,546