Common Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2014

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:

	2014	2013	2012
Basic	127,873,708	135,304,752	137,097,162
Diluted	133,651,855	140,742,922	143,314,544

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 and unexercised stock options.

	2014		2013		2012
Balance, beginning of year	132,233,167		136,017,732		137,520,019
Shares issued	332,137		139,790		2,114,168
Shares repurchased	(5,816,468	)	(3,924,355	)	(3,616,455)
Balance, end of year	126,748,836		132,233,167		136,017,732