Lease Obligations Lease Obligations (Additional Lease Information) (Narrative) (Details) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($)
Lessee, Lease, Description [Line Items]
Finance lease, weighted average remaining lease term (in years)	2 years 9 months 18 days
Finance lease, weighted average discount rate, percent	4.10%
Operating lease, weighted average remaining lease term (in years)	4 years 2 months 12 days
Operating lease, weighted average discount rate, percent	4.20%
Leases not yet commenced, future lease obligation	$ 1.4
Minimum [Member]
Lessee, Lease, Description [Line Items]
Leases not yet commenced, lease terms	1 year
Maximum [Member]
Lessee, Lease, Description [Line Items]
Leases not yet commenced, lease terms	4 years