10. Earnings Per Share and Shareholders’ Equity Transactions

The following table provides weighted average share information used in the calculation of the Company’s basic and diluted earnings per share:

	Three Months Ended						Six Months Ended
	June 30,						June 30,
(in millions, except per share data)	2018			2017			2018			2017
Basic shares used in the calculation of earnings per share		42.5			42.5			42.5			42.5
Dilutive effect of securities:
Employee stock options		0.3			0.2			0.3			0.2
Non-vested stock grants		0.3			0.1			0.3			0.2
Diluted shares used in the calculation of earnings per share		43.1			42.8			43.1			42.9
Per share effect of dilutive securities on income from continuing operations and net income	$	(0.03	)	$	(0.02	)	$	(0.05	)	$	(0.03	)

Diluted earnings per share for the three months ended June 30, 2018 and 2017 excludes 0.3 million and 1.0 million, respectively, of common shares issuable under the Company’s stock compensation plans because their effect would be antidilutive. Diluted earnings per share for the six months ended June 30, 2018 and 2017 excludes 0.3 million and 0.9 million, respectively, of common shares issuable under the Company’s stock compensation plans because their effect would be antidilutive.

The Company’s Board of Directors has authorized aggregate repurchases of the Company’s common stock of up to $900 million. Under the repurchase authorizations, the Company may repurchase, from time to time, common shares in amounts, at prices and at such times as the Company deems appropriate, subject to market conditions and other considerations. Repurchases may be executed using open market purchases, privately negotiated transactions, accelerated repurchase programs or other transactions. The Company is not required to purchase any specific number of shares or to make purchases by any certain date under this program. During the first six months of 2018, the Company purchased approximately 0.2 million shares of the Company’s common stock at a cost of $25.3 million.