Consolidated Balance Sheets - USD ($) $ in Millions	Mar. 31, 2018		Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 47.0		$ 134.1
Accounts receivable, net	271.2		237.8
Materials and supplies	160.8		150.8
Other current assets	86.9		157.4
Total current assets	565.9		680.1
Investments	46.5		44.6
Property and equipment (including concession assets), net	8,430.6		8,403.8
Other assets	85.1		70.2
Total assets	9,128.1		9,198.7
Current liabilities:
Long-term debt due within one year	36.0		38.8
Short-term borrowings	342.8		345.1
Accounts payable and accrued liabilities	445.0		587.8
Total current liabilities	823.8		971.7
Long-term debt	2,230.2		2,235.5
Deferred income taxes	1,012.7		987.2
Other noncurrent liabilities and deferred credits	130.0		138.9
Total liabilities	4,196.7		4,333.3
Stockholders' equity:
$.01 par, common stock, 400,000,000 shares authorized; 123,352,185 shares issued; 102,600,557 and 103,036,805 shares outstanding at March 31, 2018 and December 31, 2017, respectively	1.0		1.0
Additional paid-in capital	945.1		943.3
Retained earnings	3,670.2		3,611.4
Accumulated other comprehensive loss	(7.9)		(12.9)
Total stockholders’ equity	4,614.5		4,548.9
Noncontrolling interest	316.9		316.5
Total equity	4,931.4	[1]	4,865.4
Total liabilities and equity	9,128.1		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.