CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Cash flows from operating activities:
Net income	$ 41,018	$ 27,296
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	54,096	67,831
Loss on sales or disposals of long-lived assets, net	2,716	383
Loss from equity method investment	0	83
Impairment of land, buildings, vessels and equipment	174	2,769
Amortization of debt issuance costs and debt discounts/premiums	4,143	1,608
Share-based compensation expense	4,351	4,145
Change in income taxes	4,990	23,351
Changes in operating assets and liabilities:
Receivables, net	8,232	(1,328)
Prepaid expenses and other	(8,266)	12
Accounts payable, accrued expenses and other	(25,986)	(13,053)
Net cash provided by operating activities	85,468	113,097
Cash flows from investing activities:
Capital expenditures	(21,884)	(21,118)
Net proceeds from disposition of asset held for sale	325	0
Proceeds from sales of property and equipment	0	294
Loans receivable	(750)	(750)
Net cash used in investing activities	(22,309)	(21,574)
Cash flows from financing activities:
Proceeds from credit facility	64,000	35,000
Repayments under credit facility	(169,250)	(137,750)
Proceeds from common stock options exercised	215	6,146
Other	(841)	(252)
Net cash used in financing activities	(105,876)	(96,856)
Change in cash and cash equivalents	(42,717)	(5,333)
Cash and cash equivalents at the beginning of the period	164,034	164,654
Cash and cash equivalents at the end of the period	121,317	159,321
Supplemental Cash Flow Information:
Cash paid for interest, net of amounts capitalized	36,011	39,465
Cash payments (refunds) related to income taxes, net	14	(17,379)
Decrease in construction-related deposits and liabilities	(491)	(5,617)
Non-cash issuance of common stock	$ 614	$ 260