Debt (Details)	3 Months Ended	12 Months Ended
	Jun. 30, 2011 USD ($) $ / shares shares	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Debt Instrument [Line Items]
Debt		$ 6,045,167,000	$ 6,122,413,000
Long-term debt		5,829,912,000	5,886,809,000
Less current portion		215,255,000	235,604,000
Weighted average interest rate				5.50%
Unamortized debt discount		(25,538,000)
Coupon interest		174,027,000	173,484,000	$ 128,002,000
Extinguishment of Debt, Amount				275,900,000
Long-term debt maturity [Abstract]
2016		570,353,000
2017		1,509,499,000
2018		391,708,000
2019		674,125,000
2020		519,208,000
Thereafter		4,487,860,000
Total obligations		8,152,753,000
Unamortized debt discount		(25,538,000)
Less amount representing interest		(2,082,048,000)
Total		6,045,167,000	6,122,413,000
Long-term debt, less current portion		3,413,998,000	3,459,371,000
Mortgages Payable [Member]
Debt Instrument [Line Items]
Debt		$ 3,184,229,000	$ 3,246,513,000
Maturity date, start		Jun. 01, 2017
Maturity date, end		Dec. 31, 2047
Weighted average interest rate		4.50%	4.51%
Unamortized debt premium		$ (4,500,000)	$ 3,300,000
Long-term debt maturity [Abstract]
Total		3,184,229,000	3,246,513,000
Capital and Financing Lease Obligations [Member]
Debt Instrument [Line Items]
Debt		$ 2,485,520,000	$ 2,489,588,000
Maturity date		Dec. 31, 2032
Weighted average interest rate		8.08%	8.11%
Unamortized debt discount		$ 0
Long-term debt maturity [Abstract]
2016		416,239,000
2017		277,829,000
2018		256,539,000
2019		200,308,000
2020		186,342,000
Thereafter		3,230,311,000
Total obligations		4,567,568,000
Unamortized debt discount		0
Less amount representing interest		(2,082,048,000)
Total		2,485,520,000	$ 2,489,588,000
Convertible Debt [Member]
Debt Instrument [Line Items]
Debt		$ 295,397,000	$ 281,902,000
Maturity date		Jun. 15, 2018
Weighted average interest rate	2.75%	2.75%	2.75%
Unamortized debt discount		$ 20,900,000	$ 34,300,000
Principal	$ 316,300,000	316,300,000
Proceeds from debt financing	$ 308,200,000
Initial conversion rate (in shares per $1,000 of principal)	34.1006
Equivalent initial conversion price (in dollars per share) | $ / shares	$ 29.325
Conversion terms	The Notes are convertible at an initial conversion rate of 34.1006 shares of Company common stock per $1,000 principal amount of Notes (equivalent to an initial conversion price of approximately $29.325 per share), subject to adjustment. Holders may convert their Notes at their option prior to the close of business on the second trading day immediately preceding the stated maturity date only under the following circumstances: (i) during any fiscal quarter commencing after the fiscal quarter ending September 30, 2011, if the last reported sale price of the Company's common stock for at least 20 trading days (whether or not consecutive) during a period of 30 consecutive trading days ending on the last trading day of the preceding fiscal quarter is greater than or equal to 130% of the applicable conversion price on each applicable trading day; (ii) during the five business day period after any five consecutive trading day period (the "measurement period"), in which the trading price per $1,000 principal amount of notes for each trading day of that measurement period was less than 98% of the product of the last reported sale price of the Company's common stock and the applicable conversion rate on each such day; or (iii) upon the occurrence of specified corporate events. On and after March 15, 2018, until the close of business on the second scheduled trading day immediately preceding the maturity date, holders may convert their Notes at any time, regardless of the foregoing circumstances. Unconverted Notes mature at par in June 2018.
Imputed interest rate	7.50%
Expected life of convertible debt	7 years
Coupon interest		8,697,000	8,697,000	8,697,000
Amortization of discount		12,625,000	11,732,000	10,902,000
Interest expense related to convertible notes		21,322,000	20,429,000	$ 19,599,000
Number of shares of common stock covered by hedging transactions (in shares) | shares	10,784,315
Number of warrants to acquire common stock sold to Hedge Counterparties (in shares) | shares	10,784,315
Strike price of warrants (in dollars per share) | $ / shares	$ 40.25
Net cost of hedging transaction	$ 31,900,000
Conversion rate per value of notes		$ 1,000
Number of trading days for pricing		20 days
Number of consecutive trading days		30 days
Percentage minimum of applicable conversion price (in hundredths)		130.00%
Number of consecutive trading days less than 98% of test period		5 days
Applicable percentage rate for five day consecutive trading days (in hundredths)		98.00%
Long-term debt maturity [Abstract]
Unamortized debt discount		$ 20,900,000	34,300,000
Total		295,397,000	281,902,000
Construction Financing [Member]
Debt Instrument [Line Items]
Debt		$ 3,644,000	$ 24,105,000
Maturity date, start		Dec. 31, 2017
Maturity date, end		Dec. 31, 2032
Weighted average interest rate		8.00%	4.84%
Long-term debt maturity [Abstract]
Total		$ 3,644,000	$ 24,105,000
Other Notes Payable [Member]
Debt Instrument [Line Items]
Debt		$ 76,377,000	$ 80,305,000
Maturity date, start		Jun. 30, 2017
Maturity date, end		Feb. 01, 2020
Weighted average interest rate		5.33%	5.16%
Long-term debt maturity [Abstract]
Total		$ 76,377,000	$ 80,305,000
Long-term Debt [Member]
Debt Instrument [Line Items]
Debt		3,559,647,000
Unamortized debt discount		(25,538,000)
Long-term debt maturity [Abstract]
2016		154,114,000
2017		1,231,670,000
2018		135,169,000
2019		473,817,000
2020		332,866,000
Thereafter		1,257,549,000
Total obligations		3,585,185,000
Unamortized debt discount		(25,538,000)
Less amount representing interest		0
Total		3,559,647,000
Assets held for sale [Member]
Long-term debt maturity [Abstract]
Long-term debt, less current portion		$ 60,500,000	$ 60,800,000