Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 43,087	$ 57,063
Accounts receivable, net of allowance for doubtful accounts of $41,121 and $38,916, respectively	276,089	263,327
Other current assets	104,837	107,537
Total current assets	424,013	427,927
Property and equipment, net	2,749,538	2,703,695
Goodwill	2,683,787	2,681,188
Intangible assets, net	83,718	83,310
Deferred tax assets - noncurrent	3,750	3,780
Derivative instruments	59,257	73,509
Other assets	61,727	51,317
Total assets	6,065,790	6,024,726
Current liabilities:
Current portion of long-term debt	34,805	34,805
Accounts payable	92,673	80,034
Accrued salaries and benefits	102,333	105,068
Other accrued liabilities	106,046	122,958
Total current liabilities	335,857	342,865
Long-term debt	3,246,577	3,253,004
Deferred tax liabilities - noncurrent	63,858	78,520
Other liabilities	165,995	164,859
Total liabilities	3,812,287	3,839,248
Redeemable noncontrolling interests	17,570	17,754
Equity:
Preferred stock, $0.01 par value; 10,000,000 shares authorized, no shares issued
Common stock, $0.01 par value; 180,000,000 shares authorized; 86,916,624 and 86,688,199 issued and outstanding as of March 31, 2017 and December 31, 2016, respectively	869	867
Additional paid-in capital	2,499,760	2,496,288
Accumulated other comprehensive loss	(528,392)	(549,570)
Retained earnings	263,696	220,139
Total equity	2,235,933	2,167,724
Total liabilities and equity	$ 6,065,790	$ 6,024,726