Earnings per Share (Tables)

3 Months Ended

Mar. 31, 2018

Earnings per Share [Abstract]

Weighted-Average Shares Outstanding for Computation of Basic and Diluted Income per Common Share

	Three Months Ended
	March 31,
(Weighted-average shares)	2018	2017
Basic method	172,805,065	172,422,449
Dilutive stock options and restricted stock units	1,814,459	666,242
Diluted method	174,619,524	173,088,691

Anti Dilutive Securities Not Included in Computation of Diluted EPS

	Three Months Ended
		March 31,
		2018	2017
Antidilutive stock options excluded from diluted shares		3,798,792		5,029,752
Weighted average price of these options	$	50.77	$	52.26