Long-Term Debt	6 Months Ended
Jun. 30, 2013
Debt Disclosure [Abstract]
Long-Term Debt	Long-Term Debt Senior Bank Debt The Company entered into a $1.25 billion senior unsecured revolving credit facility in April 2013 (the "credit facility") which matures in April 2018. As of June 30, 2013, the current outstanding balance under the credit facility is $100.0 million. The credit facility is unsecured and contains financial covenants with respect to leverage and interest coverage, as well as customary affirmative and negative covenants, including limitations on indebtedness, liens, cash dividends, asset dispositions and fundamental corporate changes. Convertible Securities In the second quarter of 2013, the Company repurchased an aggregate of $53.4 million principal amount outstanding of its 3.95% senior convertible notes due 2038 ("2008 senior convertible notes"). In July 2013, the Company repurchased an additional $26.1 million principal amount outstanding and subsequently called the outstanding 2008 senior convertible notes for redemption on August 15, 2013. In lieu of redemption, holders of the 2008 senior convertible notes may convert their securities at any time before the close of business on August 14, 2013. The conversion rate is 7.9586 shares of Company common stock per $1,000 principal amount of 2008 senior convertible notes. The Company may elect to settle such conversions in cash or common stock (or a combination thereof). Pursuant to its call and prior repurchases, all of the Company's 2008 senior convertible notes will be canceled and retired.

Long-Term Debt

6 Months Ended

Jun. 30, 2013

Senior Bank Debt

The Company entered into a $1.25 billion senior unsecured revolving credit facility in April 2013 (the "credit facility") which matures in April 2018. As of June 30, 2013, the current outstanding balance under the credit facility is $100.0 million.

The credit facility is unsecured and contains financial covenants with respect to leverage and interest coverage, as well as customary affirmative and negative covenants, including limitations on indebtedness, liens, cash dividends, asset dispositions and fundamental corporate changes.

Convertible Securities

In the second quarter of 2013, the Company repurchased an aggregate of $53.4 million principal amount outstanding of its 3.95% senior convertible notes due 2038 ("2008 senior convertible notes").

In July 2013, the Company repurchased an additional $26.1 million principal amount outstanding and subsequently called the outstanding 2008 senior convertible notes for redemption on August 15, 2013. In lieu of redemption, holders of the 2008 senior convertible notes may convert their securities at any time before the close of business on August 14, 2013. The conversion rate is 7.9586 shares of Company common stock per $1,000 principal amount of 2008 senior convertible notes. The Company may elect to settle such conversions in cash or common stock (or a combination thereof). Pursuant to its call and prior repurchases, all of the Company's 2008 senior convertible notes will be canceled and retired.