Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Assets
Cash and cash equivalents	$ 595,639	$ 742,546
Accounts receivable, net of allowance for doubtful accounts of $105 and $105, respectively	444,953	436,560
Contract assets	148,231	146,496
Inventories	318,986	268,917
Prepaid expenses and other assets	35,277	36,018
Income taxes receivable	0	120
Total current assets	1,543,086	1,630,657
Property, plant and equipment, net of accumulated depreciation of $445,939 and $432,043, respectively	203,872	186,473
Goodwill	192,116	191,616
Deferred income taxes	4,034	4,034
Other, net	94,077	96,524
Total assets	2,037,185	2,109,304
Current liabilities:
Current installments of long-term debt and capital lease obligations	21,219	18,274
Accounts payable	383,606	362,701
Income taxes payable	20,803	11,663
Accrued liabilities	75,368	85,679
Total current liabilities	500,996	478,317
Long-term debt and capital lease obligations, less current installments	181,777	193,406
Other long-term liabilities	90,262	89,749
Deferred income taxes	20,005	8,694
Shareholders' equity:
Common stock, $0.10 par value; 145,000 shares authorized; issued and outstanding - 47,334 and 49,143, respectively	4,733	4,914
Additional paid-in capital	607,984	634,192
Retained earnings	639,779	708,181
Accumulated other comprehensive loss	(8,351)	(8,149)
Total shareholders' equity	1,244,145	1,339,138
Total liabilities and shareholders' equity	$ 2,037,185	$ 2,109,304