CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Apr. 01, 2018		Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 637,873		$ 429,843
Marketable securities	860,526		1,347,979
Accounts receivable, less allowance for doubtful accounts of $2,206 and $2,219 at April 1, 2018 and December 31, 2017, respectively	413,978		272,783
Inventories, net	131,857		107,525
Prepayments and other current assets	112,191		112,151
Total current assets	2,156,425		2,270,281
Property, plant and equipment, net	281,284		268,447
Marketable securities	89,259		125,926
Deferred tax assets	77,705		84,026
Retirement plans assets	17,928		17,491
Other assets	12,479		12,275
Acquired intangible assets, net	84,413		79,088
Goodwill	275,700		252,011
Total assets	2,995,193	[1]	3,109,545
Current liabilities:
Accounts payable	103,950		86,393
Accrued employees' compensation and withholdings	86,292		141,694
Deferred revenue and customer advances	85,892		83,614
Other accrued liabilities	64,782		59,083
Contingent consideration	15,581		24,497
Income taxes payable	34,828		59,055
Total current liabilities	391,325		454,336
Retirement plans liabilities	124,689		119,776
Long-term deferred revenue and customer advances	21,726		30,127
Deferred tax liabilities	6,185		6,720
Long-term other accrued liabilities	16,683		10,273
Long-term contingent consideration			20,605
Long-term income taxes payable	160,181		148,075
Long-term debt	369,421		365,987
Total liabilities	1,090,210		1,155,899
Commitments and contingencies (See Note Q)
SHAREHOLDERS' EQUITY
Common stock, $0.125 par value, 1,000,000 shares authorized; 193,808 and 195,548 shares issued and outstanding at April 1, 2018 and December 31, 2017, respectively	24,226		24,444
Additional paid-in capital	1,638,756		1,638,413
Accumulated other comprehensive income	25,881		18,776
Retained earnings	216,120		272,013
Total shareholders' equity	1,904,983		1,953,646
Total liabilities and shareholders' equity	$ 2,995,193		$ 3,109,545

[1] Total business assets are directly attributable to each business. Corporate assets consist of cash and cash equivalents, marketable securities and certain other assets.