Senior Bank Debt	12 Months Ended
Dec. 31, 2014
Debt Disclosure [Abstract]
Senior Bank Debt	Senior Bank Debt The Company has a $1.25 billion senior unsecured revolving credit facility (the "credit facility") which matures in April 2018. The Company pays interest on any outstanding obligations at specified rates, based either on the LIBOR rate or the prime rate as in effect from time to time. As of December 31, 2013 and 2014, the Company had outstanding borrowings under the credit facility of $525.0 million and $605.0 million, respectively, and the weighted-average interest rate on outstanding borrowings was 1.95% and 1.40%, respectively. The Company pays commitment fees on the unused portion of its credit facility. In 2013 and 2014 these fees amounted to $3.2 million and $2.8 million, respectively. On April 15, 2014, the Company entered into a $250.0 million five-year senior unsecured term loan, which matures in 2019. The Company pays interest at specified rates (based on either the LIBOR rate or the prime rate as in effect from time to time). Subject to certain conditions, the Company may borrow up to an additional $100.0 million. As of December 31, 2014, the Company had outstanding borrowings under the term loan of $250.0 million, and the weighted-average interest rate on outstanding borrowings was 1.48%. The credit facility and term loan contain financial covenants with respect to leverage and interest coverage, as well as customary affirmative and negative covenants, including limitations on priority indebtedness, liens, cash dividends, asset dispositions, fundamental corporate changes and certain customary events of default.

Senior Bank Debt

The Company has a $1.25 billion senior unsecured revolving credit facility (the "credit facility") which matures in April 2018. The Company pays interest on any outstanding obligations at specified rates, based either on the LIBOR rate or the prime rate as in effect from time to time.

As of December 31, 2013 and 2014, the Company had outstanding borrowings under the credit facility of $525.0 million and $605.0 million, respectively, and the weighted-average interest rate on outstanding borrowings was 1.95% and 1.40%, respectively. The Company pays commitment fees on the unused portion of its credit facility. In 2013 and 2014 these fees amounted to $3.2 million and $2.8 million, respectively.

On April 15, 2014, the Company entered into a $250.0 million five-year senior unsecured term loan, which matures in 2019. The Company pays interest at specified rates (based on either the LIBOR rate or the prime rate as in effect from time to time). Subject to certain conditions, the Company may borrow up to an additional $100.0 million. As of December 31, 2014, the Company had outstanding borrowings under the term loan of $250.0 million, and the weighted-average interest rate on outstanding borrowings was 1.48%.

The credit facility and term loan contain financial covenants with respect to leverage and interest coverage, as well as customary affirmative and negative covenants, including limitations on priority indebtedness, liens, cash dividends, asset dispositions, fundamental corporate changes and certain customary events of default.