Earnings Per Share (Tables)

6 Months Ended

Jun. 30, 2018

Earnings Per Share [Abstract]

Reconciliation of the Average Shares Outstanding Used to Compute Basic and Diluted Earnings per Share

The following is a reconciliation of the weighted average shares outstanding used to compute basic and diluted earnings per share:

	Three Months Ended June 30,		Six Months Ended June 30,
	2018	2017	2018	2017
Weighted average shares outstanding — Basic	139,998,308	138,972,873	139,853,748	138,866,565
Effect of dilutive securities:
Stock options	614,882	907,903	670,264	885,705
Unvested restricted stock	259,300	539,461	410,074	548,887
Unvested performance share units	198,769	241,199	197,036	162,999
Effect of dilutive securities	1,072,951	1,688,563	1,277,374	1,597,591
Weighted average shares outstanding — Diluted	141,071,259	140,661,436	141,131,122	140,464,156