Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Assets
Cash and cash equivalents	$ 676,327	$ 742,546
Accounts receivable, net of allowance for doubtful accounts of $105 and $105, respectively	403,767	436,560
Contract assets	147,623	146,496
Inventories	305,980	268,917
Prepaid expenses and other assets	31,729	36,018
Income taxes receivable	66	120
Total current assets	1,565,492	1,630,657
Property, plant and equipment, net of accumulated depreciation of $438,435 and $432,043, respectively	200,422	186,473
Goodwill	191,616	191,616
Deferred income taxes	4,034	4,034
Other, net	96,442	96,524
Total assets	2,058,006	2,109,304
Current liabilities:
Current installments of long-term debt and capital lease obligations	19,746	18,274
Accounts payable	368,625	362,701
Income taxes payable	12,808	11,663
Accrued liabilities	83,652	85,679
Total current liabilities	484,831	478,317
Long-term debt and capital lease obligations, less current installments	187,601	193,406
Other long-term liabilities	90,270	89,749
Deferred income taxes	47,973	8,694
Shareholders' equity:
Common stock, $0.10 par value; 145,000 shares authorized; issued and outstanding - 47,572 and 49,143, respectively	4,757	4,914
Additional paid-in capital	608,092	634,192
Retained earnings	640,466	708,181
Accumulated other comprehensive loss	(5,984)	(8,149)
Total shareholders' equity	1,247,331	1,339,138
Total liabilities and shareholders' equity	$ 2,058,006	$ 2,109,304