Capital Stock	3 Months Ended
Mar. 31, 2018
Equity [Abstract]
Capital Stock	Capital Stock Treasury Stock In February 2018, the Board of Directors authorized an increase of 25.0 million shares to the Company’s share repurchase program. After this authorization, the total number of shares available for repurchase is 30.1 million shares. Under the share repurchase program, the Company may purchase shares of common stock in the open market or in negotiated transactions. The timing and amount of any stock purchases are determined at the discretion of management. The Company may use the repurchased shares to fund stock compensation programs currently in existence, or for other corporate purposes. All purchases executed to date have been through open market transactions. There is no expiration date associated with the authorization to repurchase common stock of the Company. During the first three months of 2018, the Company repurchased 8.3 million shares for a total cost of $207.1 million. As of March 31, 2018, 21.7 million shares are available for repurchase under the share repurchase program. No treasury shares have been delivered or sold by the Company subsequent to the repurchase. As of March 31, 2018, 23.3 million shares were held as treasury stock. Subsequent Event. Subsequent to March 31, 2018, the Company repurchased 1.6 million shares for a total cost of $38.5 million under a Rule 10b5-1 Plan. The plan expires on April 30, 2018.

Capital Stock

Treasury Stock

In February 2018, the Board of Directors authorized an increase of 25.0 million shares to the Company’s share repurchase program. After this authorization, the total number of shares available for repurchase is 30.1 million shares. Under the share repurchase program, the Company may purchase shares of common stock in the open market or in negotiated transactions. The timing and amount of any stock purchases are determined at the discretion of management. The Company may use the repurchased shares to fund stock compensation programs currently in existence, or for other corporate purposes. All purchases executed to date have been through open market transactions. There is no expiration date associated with the authorization to repurchase common stock of the Company.

During the first three months of 2018, the Company repurchased 8.3 million shares for a total cost of $207.1 million. As of March 31, 2018, 21.7 million shares are available for repurchase under the share repurchase program.

No treasury shares have been delivered or sold by the Company subsequent to the repurchase. As of March 31, 2018, 23.3 million shares were held as treasury stock.

Subsequent Event. Subsequent to March 31, 2018, the Company repurchased 1.6 million shares for a total cost of $38.5 million under a Rule 10b5-1 Plan. The plan expires on April 30, 2018.