CONSOLIDATED BALANCE SHEETS (USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010
Current Assets:
Cash and cash equivalents	$ 406,207	$ 377,223
Accounts receivable	297,704	261,160
Unbilled services	107,677	90,729
Inventory	88,999	82,924
Deferred income taxes	38,397	35,648
Prepaid expenses and other current assets	104,556	98,127
Total Current Assets	1,043,540	945,811
Property and equipment, net	857,857	843,983
Goodwill, net	127,653	127,653
Other assets	52,496	48,095
Total Assets	2,081,546	1,965,542
Current Liabilities:
Accounts payable	44,690	34,079
Accrued payroll and benefits	105,776	107,572
Accrued expenses and other current liabilities	117,029	97,395
Unearned revenue	188,328	186,301
Short-term debt and current portion of long-term debt	10,000	45,000
Income taxes payable	10,485	28,827
Total Current Liabilities	476,308	499,174
Long-term debt	82,500	87,500
Deferred income taxes	29,881	30,531
Other liabilities	69,988	68,516
Total Liabilities	658,677	685,721
Commitments and Contingent Liabilities
Stockholders' Equity:
Preferred Stock - Par value $1.00 per share; 10,000,000 shares authorized; no shares issued and outstanding at June 30, 2011 and December 31, 2010	0	0
Common Stock - Par value $0.01 per share; 140,000,000 shares authorized; 77,978,724 and 77,391,335 shares issued and outstanding, including those held in treasury, at June 30, 2011 and December 31, 2010, respectively	780	774
Paid-in capital	666,427	639,341
Retained earnings	1,444,085	1,373,705
Accumulated other comprehensive income	53,370	277
Treasury stock at cost (17,255,908 and 17,125,878 shares at June 30, 2011 and December 31, 2010, respectively)	(741,793)	(734,276)
Total Stockholders' Equity	1,422,869	1,279,821
Total Liabilities and Stockholders' Equity	$ 2,081,546	$ 1,965,542