Common Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2018

Equity [Abstract]

Weighted Average Number of Common Shares Used In the Computation of Basic and Diluted Earnings per Share

The weighted average number of shares used in the computation of net income per share was as follows:

	2018	2017	2016
Basic	126,698,927	124,843,240	122,650,997
Diluted	128,263,558	129,017,613	128,552,838

Schedule of Changes in Shares of Common Stock Outstanding

Changes in shares of common stock outstanding, net of treasury shares, are presented below. Shares of common stock issued and outstanding do not include shares related to unissued restricted stock units (including shares held in the grantor trust).

	2018		2017		2016
Balance, beginning of year	121,514,852		121,193,599		123,307,837
Shares issued	838,508		1,052,256		281,654
Shares repurchased	(357,600	)	(731,003	)	(2,395,892)
Balance, end of year	121,995,760		121,514,852		121,193,599