CONSOLIDATED CONDENSED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Cash Flows from Operating Activities:
Net income	$ 15,939	$ 14,800
Adjustments to reconcile net income to net cash from operating activities:
Depreciation and amortization	14,659	13,793
Stock-based compensation expense	5,429	3,078
Deferred income taxes	45	348
(Gain) loss on sale of property and equipment	427	(76)
Other long-term liabilities	3,494	1,851
Other non-cash items	(427)	(197)
Changes in other components of working capital	(80,696)	(118,052)
NET CASH USED IN OPERATING ACTIVITIES	(41,130)	(84,455)
Cash Flows from Investing Activities:
Acquisition of property and equipment	(8,352)	(12,179)
Proceeds from sale of property and equipment	1,417	239
Change in restricted cash	(675)	(6,514)
NET CASH USED IN INVESTING ACTIVITIES	(7,610)	(18,454)
Cash Flows from Financing Activities:
Proceeds from debt	178,038	293,014
Repayment of debt	(113,551)	(225,684)
Business acquisition-related payments	(1,031)
Issuance of common stock and effect of cashless exercise	(1,575)	(159)
NET CASH PROVIDED BY FINANCING ACTIVITIES	61,881	67,171
Net Increase/(Decrease) in Cash and Cash Equivalents	13,141	(35,738)
Cash and Cash Equivalents at Beginning of Year	119,923	168,056
Cash and Cash Equivalents at End of Period	133,064	132,318
Supplemental Disclosure of Cash Paid For:
Interest	5,383	5,107
Income taxes	11,703	(2,902)
Supplemental Disclosure of Non-cash Transactions:
Property and equipment acquired through financing arrangements	22,332
Grant date fair value of common stock issued for services	$ 3,491	$ 439