Lease Obligations (Tables)
|12 Months Ended|
Dec. 31, 2017
|Future Minimum Rental Commitments for Non-Cancelable Operating Leases||
Certain leases contain renewal options. Future minimum rental commitments for non-cancelable operating leases as of December 31, 2017 were as follows (in millions):
Tabular disclosure of future minimum payments required in the aggregate and for each of the five succeeding fiscal years for operating leases having initial or remaining noncancelable lease terms in excess of one year and the total minimum rentals to be received in the future under noncancelable subleases as of the balance sheet date.
Reference 1: http://www.xbrl.org/2003/role/presentationRef