Earnings Per Common Share - Computation Of Basic And Diluted Net Earnings Per Share (Details) - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Earnings Per Share [Abstract]
Weighted average number of common shares outstanding - basic (in shares)	72,754	71,826	70,616
Effect of dilutive securities (in shares)	720	686	725
Weighted average number of common shares outstanding - diluted (in shares)	73,474	72,512	71,341
Options outstanding to purchase common stock excluded from computation of diluted earnings per common share (in shares)	500	900	500
Weighted average exercise price of options (in dollars per share)	$ 34.14	$ 29.34	$ 27.97