Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash flows from operating activities:
Net income (loss)	$ (215,235,000)	$ 62,375,000	$ 70,606,000
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	72,591,000	75,336,000	63,955,000
Amortization of deferred financing costs	2,394,000	1,945,000	1,780,000
Amortization of stock-based compensation	6,735,000	7,330,000	9,366,000
Provision for doubtful accounts receivable, net of write offs	(862,000)	3,236,000	(294,000)
Deferred income tax provision (benefit)	(3,823,000)	(66,000)	21,000
(Gain) loss on sale of assets	1,160,000	(12,461,000)	$ (5,870,000)
Impairment charges	152,103,000	$ 8,995,000
Gain on extinguishment of debt	(458,000)
Foreign currency (gain) loss	(160,000)	$ 1,490,000	$ 573,000
Change in operating assets and liabilities —
Accounts receivable	47,317,000	5,700,000	(17,951,000)
Prepaids and other	214,000	(476,000)	7,954,000
Accounts payable	(8,602,000)	(3,888,000)	(1,681,000)
Other accrued liabilities and other	(10,056,000)	4,332,000	(1,757,000)
Net cash provided by operating activities	43,357,000	153,848,000	126,702,000
Cash flows from investing activities:
Purchases of vessels, equipment and other fixed assets	(35,428,000)	(158,425,000)	(261,867,000)
Release of deposits held in escrow	3,683,000	5,060,000	38,286,000
Proceeds from disposition of vessels, equipment and other fixed assets	8,910,000	32,261,000	13,512,000
Net cash used in investing activities	(22,835,000)	$ (121,104,000)	$ (210,069,000)
Cash flows from financing activities:
Repuchase of 6.375% senior notes	(542,000)
Repayment of revolving loan facility	(91,000,000)
Borrowings under revolving loan facility, net	47,000,000	$ 47,167,000
Cash dividends	$ 0	(26,152,000)	$ (26,357,000)
Stock repurchases		(57,887,000)	(12,740,000)
Debt issuance costs	$ (3,566,000)	$ (4,198,000)	(1,579,000)
Proceeds from exercise of stock options			282,000
Proceeds from issuance of stock	$ 827,000	$ 1,046,000	796,000
Net cash used in financing activities	(47,281,000)	(40,024,000)	(39,598,000)
Effect of exchange rate changes on cash	(2,087,000)	(2,501,000)	(1,644,000)
Net decrease in cash and cash equivalents	(28,846,000)	(9,781,000)	(124,609,000)
Cash and cash equivalents at beginning of year	50,785,000	60,566,000	185,175,000
Cash and cash equivalents at end of year	21,939,000	50,785,000	60,566,000
Supplemental cash flow information:
Interest paid, net of interest capitalized	29,834,000	27,067,000	21,453,000
Income taxes paid, net	$ 2,048,000	$ 4,454,000	$ 3,727,000