Unaudited Condensed Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Cash flows from operating activities:
Net income	$ 55,100	$ 45,016
Adjustments to reconcile net income to net cash provided by operations:
Depreciation and amortization	56,729	46,447
Gain on sale of assets	(6,877)	(5,875)
Impairment charge	7,459
Amortization of stock-based compensation	5,607	7,521
Amortization of deferred financing costs	1,396	1,273
Provision for doubtful accounts receivable, net of write-offs	2,158	(426)
Deferred income tax provision (benefit)	(1,969)	1,007
Foreign currency transaction loss	888	830
Change in operating assets and liabilities:
Accounts receivable	(7,010)	(24,149)
Prepaids and other	(6,601)	2,975
Accounts payable	966	(7,419)
Other accrued liabilities and other	(3,891)	(9,406)
Net cash provided by operating activities	105,312	57,794
Cash flows from investing activities:
Purchases of vessels, equipment and other fixed assets	(142,523)	(210,840)
Release of deposits held in escrow	5,060	27,404
Proceeds from disposition of vessels and equipment	15,361	13,500
Net cash used in investing activities	(122,102)	(169,936)
Cash flows from financing activities:
Proceeds from borrowings under revolving credit facilities	50,045
Repayments of borrowings under revolving credit facilities	(30,703)
Cash dividends	(20,007)	(19,900)
Stock repurchases	(8,189)	(12,389)
Debt issuance costs	(2,561)	(1,579)
Proceeds from issuance of stock	787	579
Proceeds from exercise of common stock options		282
Net cash used in financing activities	(10,628)	(33,007)
Effect of exchange rate changes on cash	(485)	(1,849)
Net decrease in cash and cash equivalents	(27,903)	(146,998)
Cash and cash equivalents at beginning of the period	60,566	185,175
Cash and cash equivalents at end of period	32,663	38,177
Supplemental cash flow information:
Interest paid, net of interest capitalized	28,603	22,654
Income taxes paid, net	$ 3,585	$ 3,008