Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 82,728	$ 22,241
Adjustments to reconcile net income to net cash provided by operating activities:
Loss from discontinued operations	9	3
Depreciation and amortization	34,223	17,633
Compensation cost related to equity awards	7,525	2,290
Excess tax benefit from share-based compensation	(4,252)	(1,746)
Deferred income taxes	(33,872)	9,977
Net gain on sale of assets	(1,707)	(1,230)
Insurance proceeds received	9,315	12,521
Changes in assets and liabilities which provided (used) cash, net of effect of acquisitions:
Accounts receivable, net	(10,274)	(2,526)
Materials and supplies	(3,404)	(1,418)
Prepaid expenses and other	(2,215)	(2,496)
Accounts payable and accrued expenses	(15,383)	(27,491)
Other assets and liabilities, net	747	(9)
Net cash provided by operating activities from continuing operations	63,440	27,749
Net cash used in operating activities from discontinued operations	(9)	(3)
Net cash provided by operating activities	63,431	27,746
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchase of property and equipment	(37,908)	(50,318)
Grant proceeds from outside parties	4,355	8,437
Cash paid for acquisitions, net of cash acquired	0	(837)
Proceeds from disposition of property and equipment	2,011	1,626
Net cash used in investing activities from continuing operations	(31,542)	(41,092)
CASH FLOWS FROM FINANCING ACTIVITIES:
Principal payments on long-term borrowings, including capital leases	(139,475)	(56,461)
Proceeds from issuance of long-term debt	73,362	64,716
Debt amendment costs	(1,543)	0
Proceeds from employee stock purchases	5,722	6,210
Treasury stock purchases	(6,995)	(1,757)
Dividends paid on Series A-1 Preferred Stock	(2,139)	0
Excess tax benefit from share-based compensation	4,252	1,746
Net cash (used in)/provided by financing activities from continuing operations	(66,816)	14,454
EFFECT OF EXCHANGE RATE CHANGES ON CASH AND CASH EQUIVALENTS	(509)	361
(DECREASE)/INCREASE IN CASH AND CASH EQUIVALENTS	(35,436)	1,469
CASH AND CASH EQUIVALENTS, beginning of period	64,772	27,269
CASH AND CASH EQUIVALENTS, end of period	$ 29,336	$ 28,738