Condensed Consolidated Balance Sheets (USD $) In Millions, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Current Assets:
Cash and cash equivalents	$ 223.7	$ 114.5
Accounts receivable, net	196.7	182.3
Deferred income taxes	9.0	9.1
Prepaid expenses and other assets	48.8	43.0
Total current assets	478.2	348.9
Investment in terminal joint venture	60.1	57.6
Property and equipment, net	721.4	735.4
Goodwill and intangible assets, net	30.8	31.2
Other long-term assets	74.1	75.2
Total assets	1,364.6	1,248.3
Current Liabilities:
Current portion of long-term debt	17.1	12.5
Accounts payable	127.6	124.0
Payroll and vacation benefits	17.3	16.9
Self-insured liabilities	20.8	15.1
Accrued and other liabilities	38.9	32.1
Total current liabilities	221.7	200.6
Long-term Liabilities:
Long-term debt	362.8	273.6
Deferred income taxes	330.1	326.1
Employee benefit plans	72.6	74.4
Self-insured claims and other liabilities	35.4	35.4
Total long-term liabilities	800.9	709.5
Commitments and Contingencies (Note 6)
Shareholders' Equity:
Capital stock	32.1	32.1
Additional paid in capital	264.8	261.9
Accumulated other comprehensive loss	(22.7)	(23.5)
Retained earnings	67.8	67.7
Total shareholders' equity	342.0	338.2
Total liabilities and shareholders' equity	$ 1,364.6	$ 1,248.3