CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Cash flows from operating activities:
Net income	$ 88.7	$ 59.6
Depreciation	59.9	53.6
Amortization	3.2	3.1
Loss on debt extinguishment	0.2	11.6
Asset impairment charges	0	6.2
Stock-based compensation	15.6	11.8
Other non-cash items, net	(4.0)	(4.2)
Changes in assets and liabilities	(11.9)	(24.1)
Net cash provided by operating activities	151.7	117.6
Cash flows from investing activities:
Capital expenditures	(113.1)	(98.4)
Purchases of short-term investments	(13.3)	(27.3)
Sales and maturities of short-term investments	18.3	32.1
Other, net	(2.9)	0.3
Net cash used in investing activities	(111.0)	(93.3)
Cash flows from financing activities:
Borrowings under revolving credit agreements	249.8	474.8
Repayments under revolving credit agreements	(241.3)	(381.8)
Repayments of long-term debt	(29.9)	(215.9)
Issuance of long-term debt	43.3	168.0
Debt issuance costs	0	(7.4)
Dividend payments	(19.7)	(18.3)
Excess tax benefit from employee stock plans	4.4	2.3
Shares repurchased for employee tax withholdings	(5.2)	(2.2)
Proceeds from stock option exercises	15.1	5.0
Employee stock purchase plan contributions	1.9	1.6
Net cash provided by financing activities	18.4	26.1
Effect of exchange rates on cash	0.7	1.0
Net increase in cash and cash equivalents	59.8	51.4
Cash, including cash equivalents at beginning of period	161.9	91.8
Cash, including cash equivalents at end of period	$ 221.7	$ 143.2