Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Current Assets:
Cash and cash equivalents	$ 1,132,901	$ 1,051,099
Accounts receivable, less allowance for doubtful accounts of $12,688 at March 31, 2018 and $12,858 at December 31, 2017	1,326,168	1,414,741
Deferred contract costs	120,861	0
Other	58,161	75,612
Total current assets	2,638,091	2,541,452
Property and equipment, less accumulated depreciation and amortization of $433,280 at March 31, 2018 and $420,282 at December 31, 2017	531,068	525,203
Goodwill	7,927	7,927
Deferred Federal and state income taxes, net	7,402	13,207
Other assets, net	27,993	29,219
Total assets	3,212,481	3,117,008
Current Liabilities:
Accounts payable	812,200	866,305
Accrued expenses, primarily salaries and related costs	222,212	206,320
Contract liabilities	147,236	0
Federal, state and foreign income taxes	17,233	20,494
Total current liabilities	1,198,881	1,093,119
Noncurrent Federal income taxes payable	31,334	29,516
Commitments and contingencies
Shareholders' Equity:
Preferred stock, none issued	0	0
Common stock, par value $0.01 per share. Issued and outstanding 174,308 shares at March 31, 2018 and 176,374 shares at December 31, 2017	1,743	1,764
Additional paid-in capital	1,198	546
Retained earnings	2,041,520	2,063,512
Accumulated other comprehensive loss	(64,992)	(73,964)
Total shareholders’ equity	1,979,469	1,991,858
Noncontrolling interest	2,797	2,515
Total equity	1,982,266	1,994,373
Total liabilities and equity	$ 3,212,481	$ 3,117,008