Consolidated Balance Sheets - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 1,023.0	$ 831.8
Marketable investments	27.8	122.0
Accounts receivable, no allowance for 2016 and 2015	214.5	192.8
Inventories, net	100.0	81.3
Other current assets	59.5	47.4
Total current assets	1,424.8	1,275.3
Marketable investments	2.3	38.0
Goodwill and other intangible assets, net	33.8	28.4
Property, plant, and equipment, net	489.3	495.8
Deferred tax assets, net	178.3	192.7
Other non-current assets	197.1	154.2
Total assets	2,325.6	2,184.4
Current liabilities:
Accounts payable and accrued expenses	104.2	103.4
Share tracking awards plan	194.8	274.5
Other current liabilities	33.5	62.8
Total current liabilities	332.5	440.7
Non-current liabilities:
Other non-current liabilities	130.9	144.0
Total liabilities	463.4	584.7
Commitments and contingencies-Note 9
Temporary equity	10.9	11.1
Stockholders' equity:
Common stock, par value $.01, 245,000,000 shares authorized, 69,340,985 and 68,987,919 shares issued, and 42,965,856 and 45,760,845 shares outstanding at December 31, 2016 and 2015, respectively	0.7	0.7
Additional paid-in capital	1,813.5	1,790.6
Accumulated other comprehensive loss	(16.8)	(20.4)
Treasury stock, 26,375,129 and 23,227,074 shares at December 31, 2016 and 2015, respectively	(2,379.6)	(1,902.1)
Retained earnings	2,433.5	1,719.8
Total stockholders' equity	1,851.3	1,588.6
Total liabilities and stockholders' equity	2,325.6	2,184.4
Preferred stock
Stockholders' equity:
Preferred stock, par value $.01, 10,000,000 shares authorized, no shares issued
Series A junior participating preferred stock
Stockholders' equity:
Preferred stock, par value $.01, 10,000,000 shares authorized, no shares issued