Federal Income Taxes (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Income Tax Contingency [Line Items]
Effective income tax rate	27.30%	22.60%
Federal income tax rate	34.00%	34.00%
Material unrecognized tax benefits or accrued interest and penalties	$ 0.0
State and Local Jurisdiction [Member] | Commonwealth of Pennsylvania [Member]
Income Tax Contingency [Line Items]
Net operating loss carryforwards	$ 8.7	$ 7.4
Minimum [Member]
Income Tax Contingency [Line Items]
Open tax year for examinations	2013
Maximum [Member]
Income Tax Contingency [Line Items]
Open tax year for examinations	2015