CONDENSED CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Current assets:
Cash and cash equivalents	$ 146,324	$ 15,028
Short-term investments	19,608	39,939
Accounts receivable, net	328,581	254,799
Income tax receivable	2,834	4,903
Inventories	20,539	17,916
Prepaid and other current assets	8,557	9,609
Total current assets	526,443	342,194
Property and equipment, net	352,833	350,725
Goodwill	1,405,895	1,389,965
Other	33,699	34,776
Total assets	2,318,870	2,117,660
Current liabilities:
Current installments of long-term obligations	307,128	397,132
Accounts payable	68,887	53,294
Accrued expenses:
Compensation and benefits	32,459	33,142
Liability insurance	19,183	19,990
Other current liabilities	53,765	54,316
Deferred income taxes	8,972	8,769
Total current liabilities	490,394	566,643
Long-term obligations, excluding current installments	496,705	256,778
Deferred income taxes and other taxes	419,912	408,325
Total liabilities	1,407,011	1,231,746
Commitments and contingencies:
Stockholders' equity:
Common stock	864	870
Additional paid-in capital	721,441	707,080
Retained earnings	189,586	177,964
Accumulated other comprehensive (loss) income	(32)	0
Total stockholders' equity	911,859	885,914
Total liabilities and stockholders' equity	$ 2,318,870	$ 2,117,660