Consolidated Balance Sheets - USD ($) $ in Millions	Jun. 30, 2018		Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 61.1		$ 134.1
Accounts receivable, net	250.0		237.8
Materials and supplies	154.0		150.8
Other current assets	62.7		157.4
Total current assets	527.8		680.1
Investments	45.6		44.6
Property and equipment (including concession assets), net	8,595.7		8,403.8
Other assets	94.0		70.2
Total assets	9,263.1		9,198.7
Current liabilities:
Long-term debt due within one year	10.8		38.8
Short-term borrowings	0.0		345.1
Accounts payable and accrued liabilities	430.1		587.8
Total current liabilities	440.9		971.7
Long-term debt	2,682.3		2,235.5
Deferred income taxes	1,020.8		987.2
Other noncurrent liabilities and deferred credits	122.9		138.9
Total liabilities	4,266.9		4,333.3
Stockholders' equity:
$.01 par, common stock, 400,000,000 shares authorized; 123,352,185 shares issued; 102,126,882 and 103,036,805 shares outstanding at June 30, 2018 and December 31, 2017, respectively	1.0		1.0
Additional paid-in capital	946.4		943.3
Retained earnings	3,731.7		3,611.4
Accumulated other comprehensive loss	(7.6)		(12.9)
Total stockholders’ equity	4,677.6		4,548.9
Noncontrolling interest	318.6		316.5
Total equity	4,996.2	[1]	4,865.4
Total liabilities and equity	9,263.1		9,198.7
$25 Par Preferred Stock [Member]
Stockholders' equity:
$25 par, 4% noncumulative, preferred stock, 840,000 shares authorized, 649,736 shares issued, 242,170 shares outstanding	$ 6.1		$ 6.1

[1] The Company reclassified $0.7 million of stranded tax effects out of accumulated other comprehensive loss and into retained earnings during the first quarter of 2018, due to the adoption of ASU No. 2018-02, Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income. For additional discussion, see Note 1 - Basis of Presentation.