Significant Accounting Policies - Weighted-Average Shares Used to Calculate Basic and Diluted EPS (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Earnings Per Share (EPS) [Abstract]
Basic shares	67,620	67,550	67,434
Dilutive shares	164	142	160
Diluted shares	67,784	67,692	67,594