Nature of Operations and Significant Accounting Policies - Narrative (Details) mi in Thousands, $ in Millions		1 Months Ended	3 Months Ended		6 Months Ended
	Jun. 05, 2017	Jun. 30, 2017 USD ($) state mi	Jun. 30, 2017 USD ($) state employee mi	Mar. 31, 2017 employee	Jun. 30, 2017 USD ($) state employee mi	Dec. 30, 2016 USD ($)
Background
Total number of rail route miles | mi		21	21		21
Number of states rail network serves | state		23	23		23
Allowance for Doubtful Accounts
Allowance for doubtful accounts		$ 24	$ 24		$ 24	$ 33
Other Items [Abstract]
Shareholder vote percent	93.00%
Chief Executive Officer
Other Items [Abstract]
Reimbursement payment		55
Lump sum cash payment owed		$ 29	$ 29		$ 29
Management Streamlining Initiative
Other Items [Abstract]
Workforce reduction (number of employees) | employee			186	765	951
Payments for restructuring					$ 129
Management Streamlining Initiative | Severance
Other Items [Abstract]
Payments for restructuring					$ 62