Unaudited Condensed Consolidated Statements of Cash Flows (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Cash flows from operating activities:
Net income (loss)	$ (5,126,000)	$ 16,557,000
Adjustments to reconcile net income to net cash provided by (used in) operations:
Depreciation and amortization	18,488,000	18,357,000
Stock-based compensation	1,804,000	1,640,000
Amortization of deferred financing costs	582,000	463,000
Provision for doubtful accounts receivable, net of write-offs	(892,000)	(226,000)
Deferred income tax benefit	(4,534,000)	(245,000)
Foreign currency transaction (gain) loss	566,000	(242,000)
Change in operating assets and liabilities:
Accounts receivable	10,722,000	(2,699,000)
Prepaids and other	(3,559,000)	(3,044,000)
Accounts payable	(3,763,000)	(2,756,000)
Other accrued liabilities and other	(11,730,000)	(10,156,000)
Net cash provided by operating activities	2,558,000	17,649,000
Cash flows from investing activities:
Purchases of vessels, equipment and other fixed assets	(11,618,000)	(96,117,000)
Release of deposits held in escrow	3,683,000
Proceeds from disposition of vessels and equipment	715,000
Net cash used in investing activities	(7,220,000)	(96,117,000)
Cash flows from financing activities:
Proceeds from borrowings under revolving loan facility	16,000,000	50,045,000
Cash dividends		(6,824,000)
Debt issuance costs	(1,191,000)
Proceeds from issuance of stock	307,000	288,000
Net cash provided by financing activities	15,116,000	43,509,000
Effect of exchange rate changes on cash	(1,392,000)	98,000
Net increase (decrease) in cash and cash equivalents	9,062,000	(34,861,000)
Cash and cash equivalents at beginning of the period	50,785,000	60,566,000
Cash and cash equivalents at end of period	59,847,000	25,705,000
Supplemental cash flow information:
Interest paid, net of interest capitalized	15,361,000	14,407,000
Income taxes paid, net	$ 396,000	$ 859,000