Unaudited Condensed Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Cash flows from operating activities:
Net income	$ 45,016	$ 24,161
Adjustments to reconcile net income to net cash provided by operations:
Depreciation and amortization	46,447	44,576
Gain on sale of assets	(5,875)	(8,744)
Impairment charge		859
Amortization of stock-based compensation	7,521	5,530
Amortization of deferred financing costs	1,273	2,390
Loss on extinguishment of debt		1,554
Provision for doubtful accounts receivable, net of write-offs	(426)	(59)
Deferred income tax provision	1,007	(1,448)
Foreign currency transaction gain	830	681
Change in operating assets and liabilities:
Accounts receivable	(24,149)	(7,792)
Prepaids and other	2,975	(3,064)
Accounts payable	(7,419)	4,758
Other accrued liabilities and other	(9,406)	1,763
Net cash provided by operating activities	57,794	65,165
Cash flows from investing activities:
Purchases of vessels, equipment and other fixed assets	(210,840)	(105,491)
Release of deposits held in escrow	27,404	(52,390)
Proceeds from disposition of vessels and equipment	13,500	40,565
Net cash used in investing activities	(169,936)	(117,316)
Cash flows from financing activities:
Cash dividends	(19,900)
Stock repurchases	(12,389)
Debt issuance costs	(1,579)	(11,706)
Proceeds from issuance of stock	579	595
Proceeds from issue of 6.375% Senior Notes		300,000
Repayment of 7.75% Senior Notes		(160,000)
Repayments of secured credit facility		(101,667)
Borrowings under revolving loan facility, net		44,005
Debt extinguishment cost		(2,274)
Proceeds from exercise of stock options	282	2,398
Net cash (used in) provided by financing activities	(33,007)	71,351
Effect of exchange rate changes on cash	(1,849)	976
Net increase (decrease) in cash and cash equivalents	(146,998)	20,176
Cash and cash equivalents at beginning of the period	185,175	128,817
Cash and cash equivalents at end of period	38,177	148,993
Supplemental cash flow information:
Interest paid, net of interest capitalized	22,654	18,111
Income taxes paid, net	$ 3,008	$ 3,112