Long-term Debt - Textual (Details)	1 Months Ended							3 Months Ended	12 Months Ended
	Nov. 30, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Sep. 30, 2017 USD ($)	May 31, 2017 USD ($) shares	Mar. 31, 2015 USD ($)	Nov. 30, 2013 USD ($) shares	Mar. 31, 2017 shares	Dec. 31, 2019 USD ($) shares	Dec. 31, 2018 USD ($) shares	Dec. 31, 2017 USD ($) shares	Jan. 01, 2019 USD ($)	May 01, 2017	Mar. 31, 2016	Sep. 30, 2015 USD ($)	Aug. 31, 2015 USD ($)	Jan. 31, 2015 USD ($)	Sep. 30, 2014 USD ($)	Sep. 30, 2012 USD ($)	Sep. 11, 2012
Debt Instrument [Line Items]
Loss on early extinguishment of debt									$ 7,700,000	$ 0	$ 10,700,000
Senior secured leverage ratio maximum									2
Conversion of convertible debt									$ 0	$ 0	$ 319,400,000
Convertible senior subordinated notes (shares) | shares									0	0	4,000,000.0
Finance lease obligations									$ 384,100,000
Term Loan Facilities
Debt Instrument [Line Items]
Maximum leverage ratio under the financial covenants	4.50
Senior Notes
Debt Instrument [Line Items]
Redemption price, (percent)									101.00%
Convertible Preferred Stock
Debt Instrument [Line Items]
Shares exchanged for convertible debt (shares) | shares							257,110
Convertible debt dividend rate (percent)							6.50%
Revolving Credit Facility
Debt Instrument [Line Items]
Notes payable									$ 45,000,000.0	$ 30,000,000.0
The Credit Agreement
Debt Instrument [Line Items]
Amounts outstanding under letter of credit facility									$ 38,900,000	$ 37,400,000
The Credit Agreement | Term Loan Facilities
Debt Instrument [Line Items]
Commitment fee (percent)	0.375%
Senior secured leverage ratio maximum	2
Payment limit under the credit agreement's negative covenant	$ 200,000,000
Maximum leverage ratio under the financial covenants	4.25
The Credit Agreement | Fed Funds Effective Rate Overnight Index Swap Rate | Term Loan Facilities
Debt Instrument [Line Items]
Spread on variable rate (percent)	0.50%
The Credit Agreement | LIBOR | Term Loan Facilities
Debt Instrument [Line Items]
Spread on variable rate (percent)	1.50%
The Credit Agreement | Term loan facilities
Debt Instrument [Line Items]
Credit facility borrowing capacity	$ 270,000,000
Percentageof aggregate principal amount outstanding (percent)	1.25%
The Credit Agreement | Revolving Credit Facility
Debt Instrument [Line Items]
Credit facility borrowing capacity	$ 1,000,000,000
Applicable interest rate under credit facility (percent)									3.20%	3.90%
The Credit Agreement | Letter of Credit
Debt Instrument [Line Items]
Credit facility borrowing capacity	260,000,000
2017 Credit Agreement | Term loan facilities
Debt Instrument [Line Items]
Credit facility borrowing capacity				$ 300,000,000
Percentageof aggregate principal amount outstanding (percent)				1.25%
Repayments of debt				$ 110,000,000
2017 Credit Agreement | Revolving Credit Facility
Debt Instrument [Line Items]
Credit facility borrowing capacity				700,000,000
2017 Credit Agreement | Letter of Credit
Debt Instrument [Line Items]
Credit facility borrowing capacity				$ 260,000,000
5.125% Senior Notes due 2023 | Senior Notes
Debt Instrument [Line Items]
Notes payable									$ 297,300,000	$ 296,600,000
Aggregate principal amount						$ 300,000,000
Net proceeds for offering						$ 295,000,000
Debt instrument interest rate (percent)						5.125%			5.125%	5.125%
Effective interest rate (percent)						5.40%
5.75% Senior Notes due 2024 | Senior Notes
Debt Instrument [Line Items]
Notes payable									$ 697,300,000	$ 1,194,700,000
Repayments of debt	$ 404,000,000		$ 102,000,000
Redemption price, (percent)	100.958%		101.917%
Aggregate principal amount																$ 350,000,000	$ 400,000,000	$ 175,000,000	$ 275,000,000
Debt issue price as percentage of principal (percent)																100.50%	102.00%	103.625%
Debt instrument interest rate (percent)									5.75%	5.75%										5.75%
Effective interest rate (percent)																				5.80%
Debt redeemed	$ 400,000,000		$ 100,000,000
5.75% Senior Notes due 2025 | Senior Notes
Debt Instrument [Line Items]
Notes payable									$ 345,600,000	$ 345,000,000.0
Aggregate principal amount															$ 350,000,000
Debt instrument interest rate (percent)									5.75%	5.75%				5.75%	5.75%
Effective interest rate (percent)															6.00%
4.50% Senior Notes due 2028 | Senior Notes
Debt Instrument [Line Items]
Notes payable									$ 491,700,000	$ 0
Redemption price, (percent)		4.70%
Aggregate principal amount		$ 500,000,000
Debt instrument interest rate (percent)		4.50%							4.50%
4.75% Senior Notes due 2030 | Senior Notes
Debt Instrument [Line Items]
Notes payable									$ 491,700,000	$ 0
Redemption price, (percent)		5.00%
Aggregate principal amount		$ 500,000,000
Debt instrument interest rate (percent)		4.75%							4.75%
2.00% Convertible Senior Subordinated Notes due 2043 [Member] | Senior Notes
Debt Instrument [Line Items]
Debt instrument interest rate (percent)									4.75%
2.00% Convertible Senior Subordinated Notes due 2043 [Member] | Senior Subordinated Notes [Member]
Debt Instrument [Line Items]
Repayments of debt					$ 600,000
Aggregate principal amount							$ 320,000,000
Debt instrument interest rate (percent)							2.00%
Effective interest rate (percent)													6.00%
Debt redeemed					$ 320,000,000
Debt instrument conversion rate					0.0272221
Conversion of convertible debt					$ 319,400,000
Conversion of convertible debt, net of tax (shares) | shares					8,900,000
Shares issued due to make-whole premium (in shares) | shares					200,000
Convertible senior subordinated notes (shares) | shares								8,600,000
Accounting Standards Update 2016-02
Debt Instrument [Line Items]
Finance lease obligations												$ 52,000,000