Contractual interest rate for funds borrowed, under the debt agreement.

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Carrying amount of long-term debt, net of unamortized discount or premium, including current and noncurrent amounts. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Debt - Summary of Debt (Details) - USD ($) $ in Thousands	12 Months Ended
Debt - Summary of Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Sep. 05, 2014	Oct. 22, 2013	Jun. 26, 2012	Mar. 25, 2008
Debt Instrument [Line Items]
Long-term debt	$ 2,309,200	$ 2,355,400
Less current portion	6,500	6,500
Total long-term debt	$ 2,302,700	$ 2,348,900
Weighted-average interest rate	3.67%	3.56%
Line of Credit
Debt Instrument [Line Items]
Long-term debt	$ 0	$ 0
Stated interest rate	0.00%	0.00%
Credit facility, expiration date	Oct. 18, 2018
Five-Year Term Loan, due October 2018 \| Unsecured Debt
Debt Instrument [Line Items]
Long-term debt	$ 25,000	$ 65,000
Debt instrument, maturity date	Oct. 18, 2018
Seven-Year Term Loan, due October 2020 \| Unsecured Debt
Debt Instrument [Line Items]
Long-term debt	$ 637,000	643,500
Debt instrument, maturity date	Oct. 18, 2020
6.50% Senior Notes due March 2018 \| Senior Notes
Debt Instrument [Line Items]
Long-term debt	$ 150,000	$ 150,000
Stated interest rate	6.50%	6.50%				6.50%
Debt instrument, maturity date	Mar. 15, 2018
3.90% Senior Notes, due June 2022 \| Senior Notes
Debt Instrument [Line Items]
Long-term debt	$ 399,700	$ 399,700
Stated interest rate	3.90%	3.90%			3.90%
Debt instrument, maturity date	Jun. 15, 2022
Senior notes, discount	$ 300	$ 300
4.50% Senior Notes, due November 2023 \| Senior Notes
Debt Instrument [Line Items]
Long-term debt	$ 698,500	$ 698,300
Stated interest rate	4.50%	4.50%		4.50%
Debt instrument, maturity date	Nov. 01, 2023
Senior notes, discount	$ 1,500	$ 1,700
3.65% Senior Notes, due September 2024 \| Senior Notes
Debt Instrument [Line Items]
Long-term debt	$ 399,000	$ 398,900
Stated interest rate	3.65%	3.65%	3.65%
Debt instrument, maturity date	Sep. 15, 2024
Senior notes, discount	$ 1,000	$ 1,100
Current Portion of Long-term Debt
Debt Instrument [Line Items]
Stated interest rate	2.05%	1.79%
Long-term Debt, Excluding Current Portion
Debt Instrument [Line Items]
Weighted-average interest rate	3.67%	3.56%
London Interbank Offered Rate (LIBOR) \| Five-Year Term Loan, due October 2018 \| Unsecured Debt
Debt Instrument [Line Items]
Stated interest rate	1.80%	1.54%
London Interbank Offered Rate (LIBOR) \| Seven-Year Term Loan, due October 2020 \| Unsecured Debt
Debt Instrument [Line Items]
Stated interest rate	2.05%	1.79%