Long-Term Debt Senior Notes (Details) - USD ($)	3 Months Ended			9 Months Ended
	Sep. 30, 2016	Mar. 31, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Aug. 12, 2016	Jun. 30, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 2,803,736,000			$ 2,803,736,000				$ 2,350,000,000
Unamortized Debt Issuance Expense	(38,338,000)			(38,338,000)				(34,030,000)
Senior Notes, Noncurrent	2,765,398,000			2,765,398,000				2,315,970,000
Gain (Loss) on Extinguishment of Debt	0		$ 0	15,722,000	$ (16,578,000)
Proceeds from Debt, Net of Issuance Costs				166,681,000	$ 0
Convertible Debt, Noncurrent	$ 128,925,000			128,925,000				0
Capped Call Transaction Costs				$ 24,183,000
Capped Call, Cap Price	$ 60.00			$ 60.00
6.50% Senior Notes Due 2021 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 346,955,000			$ 346,955,000				350,000,000
Unamortized Debt Issuance Expense	(3,547,000)			(3,547,000)				(4,106,000)
Senior Notes, Noncurrent	343,408,000			343,408,000				345,894,000
6.125% Senior Notes Due 2022 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	561,796,000			561,796,000				600,000,000
Unamortized Debt Issuance Expense	(7,274,000)			(7,274,000)				(8,714,000)
Senior Notes, Noncurrent	554,522,000			554,522,000				591,286,000
6.50% Senior Notes Due 2023 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	394,985,000			394,985,000				400,000,000
Unamortized Debt Issuance Expense	(4,618,000)			(4,618,000)				(5,231,000)
Senior Notes, Noncurrent	390,367,000			390,367,000				394,769,000
5% Senior Notes Due 2024 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	500,000,000			500,000,000				500,000,000
Unamortized Debt Issuance Expense	(6,763,000)			(6,763,000)				(7,455,000)
Senior Notes, Noncurrent	493,237,000			493,237,000				492,545,000
5.625% Senior Notes Due 2025 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	500,000,000			500,000,000				500,000,000
Unamortized Debt Issuance Expense	(7,845,000)			(7,845,000)				(8,524,000)
Senior Notes, Noncurrent	492,155,000			492,155,000				491,476,000
6.75% Senior Notes Due 2026 [Domain]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	500,000,000			500,000,000				0
Unamortized Debt Issuance Expense	(8,291,000)			(8,291,000)				0
Senior Notes, Noncurrent	491,709,000			491,709,000				0
1.50% Senior Convertible Notes Due 2021 [Domain]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 172,500,000			172,500,000				0
Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Covenant Compliance, Dividends Excluded From Computation				$ 6,500,000
Debt Instrument, Repurchased Face Amount		$ 46,300,000
Debt Instrument, Repurchased Settlement Amount		29,900,000
Gain (Loss) on Extinguishment of Debt		15,722,000
Debt Instrument, Repurchase Discount		16,400,000
Amortization of Debt Issuance Costs Related to Repurchase of Debt Instrument		$ 700,000
Senior Notes [Member] | 6.50% Senior Notes Due 2021 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	6.50%			6.50%
Senior Notes [Member] | 6.125% Senior Notes Due 2022 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	6.125%			6.125%
Senior Notes [Member] | 6.50% Senior Notes Due 2023 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	6.50%			6.50%
Senior Notes [Member] | 5% Senior Notes Due 2024 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	5.00%			5.00%
Senior Notes [Member] | 5.625% Senior Notes Due 2025 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	5.625%			5.625%
Senior Notes [Member] | 6.75% Senior Notes Due 2026 [Domain]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	6.75%			6.75%
Debt Instrument, Face Amount	$ 500,000,000			$ 500,000,000
Proceeds from Debt, Net of Paid and Accrued Issuance Costs				491,600,000
Debt Issuance Costs, Gross	$ 8,400,000			$ 8,400,000
Senior Notes [Member] | 1.50% Senior Convertible Notes Due 2021 [Domain]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	1.50%			1.50%
Convertible Debt [Member] | 1.50% Senior Convertible Notes Due 2021 [Domain]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 172,500,000			$ 172,500,000
Unamortized Debt Issuance Expense	(4,311,000)			(4,311,000)
Debt Issuance Costs, Gross	5,800,000			5,800,000
Proceeds from Debt, Net of Issuance Costs				$ 166,700,000
Debt Instrument, Convertible, Threshold Trading Days				20
Debt Instrument, Convertible, Threshold Consecutive Trading Days				30 days
Debt Instrument, Convertible, Threshold Percentage of Stock Price Trigger				130.00%
Debt Instrument, Convertible, Threshold Business Days, Trading Price Trigger				5 days
Debt Instrument, Convertible, Threshold Trading Days, Trading Price Trigger				5 days
Debt Instrument, Principal Amount of Note	$ 1,000			$ 1,000
Debt Instrument, Convertible, Threshold Percentage of Trading Price Trigger				98.00%
Debt Instrument, Convertible, Conversion Ratio				24.6914
Debt Instrument, Convertible, Conversion Price	$ 40.50			$ 40.50
Debt Instrument, Convertible, Comparable Yield				7.25%
Debt Instrument, Convertible, Initial Fair Value of Liability Component						$ 132,300,000
Debt Instrument, Convertible, Carrying Amount of Equity Component	$ (40,217,000)			$ (40,217,000)		$ (40,200,000)
Amortization of Debt Discount (Premium)				953,000
Convertible Debt, Noncurrent	128,925,000			128,925,000
Revolving Credit Facility [Member] | Line of Credit [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Current Borrowing Capacity	$ 1,106,875,000			$ 1,106,875,000			$ 1,250,000,000	$ 1,500,000,000
Debt Issuance Costs, Gross							$ 3,100,000