Income Taxes (Provision for Income Taxes) (Narrative) (Details) - State and local jurisdiction [Member] $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($)
Income Taxes
Tax credit carryforwards available for state tax purposes, net of federal impact	$ 9.4
Net operating loss carryforwards available for state tax purposes	$ 9.8
Tax credit carryforwards available for state tax purposes, expiration year	2024
Earliest tax year [Member]
Income Taxes
Operating loss carryforwards available for state tax purposes, expiration year	2022
Latest tax year [Member]
Income Taxes
Operating loss carryforwards available for state tax purposes, expiration year	2028