Consolidated Statements of Cash Flows (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011
Operating activities:
Net income	$ 196.2	$ 135.8
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	97.1	91.2
Deferred income taxes	81.5	77.2
Equity in net earnings of unconsolidated affiliates	(10.7)	(8.9)
Share-based compensation	5.7	5.3
Excess tax benefit from share-based compensation	(14.1)	0
Deferred compensation	7.3	9.1
Elimination of deferred statutory profit sharing liability	(47.8)	0
Distributions from unconsolidated affiliates	7.3	6.6
Cash payments related to hurricane damage	0	(1.1)
Insurance proceeds related to hurricane damage	0	21.7
Gain on sale of assets	0	(0.2)
Debt retirement costs	18.0	10.3
Changes in working capital items:
Accounts receivable	(20.5)	(35.8)
Materials and supplies	(6.6)	(13.8)
Other current assets	6.3	11.2
Accounts payable and accrued liabilities	(1.2)	(5.4)
Other, net	(8.4)	(34.3)
Net cash provided by operating activities	310.1	268.9
Investing activities:
Capital expenditures	(214.8)	(171.8)
Property investments in MSLLC	(26.6)	(24.2)
Insurance proceeds related to hurricane damage	0	8.3
Proceeds from disposal of property	6.4	4.9
Other, net	3.7	8.7
Net cash used for investing activities	(231.3)	(174.1)
Financing activities:
Proceeds from issuance of long-term debt	329.6	200.0
Repayment of long-term debt	(349.4)	(209.6)
Debt costs	(19.3)	(12.9)
Proceeds from employee stock plans	0.9	1.2
Excess tax benefit from share-based compensation	14.1	0
Dividends paid	(21.6)	(2.9)
Net cash used for financing activities	(45.7)	(24.2)
Cash and cash equivalents:
Net increase during each period	33.1	70.6
At beginning of year	72.4	85.4
At end of period	$ 105.5	$ 156.0