Income Taxes (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax [Line Items]
Tax computed at statutory rate		35.00%	35.00%	35.00%
Tax year audited		2014
Reclassification of certain tax effects from accumulated other comprehensive loss
Change in provisional tax benefit		5.8
Re-measurement to income tax expense		19.5
Income tax benefit from AMT credit carryover		10.2
Scenario, Plan [Member]
Income Tax [Line Items]
Tax computed at statutory rate	21.00%
State [Member] | 2004 Through 2017 Tax Years [Member]
Income Tax [Line Items]
Net operating loss carryforwards		$ 31.4
Operating loss carryforwards, originated tax years		2004 through 2017
Net operating loss carryforwards, expiration date		Dec. 31, 2024
Federal And State [Member] | From 2011 Through 2017 Tax Years [Member]
Income Tax [Line Items]
Tax credit carryforwards		$ 21.3
Tax credit carryforwards, originated tax years		2011 through 2017
Minimum [Member] | Federal And State [Member] | From 2011 Through 2017 Tax Years [Member]
Income Tax [Line Items]
Tax credit carryforwards, expiration date		Dec. 31, 2021
Maximum [Member] | Federal And State [Member] | From 2011 Through 2017 Tax Years [Member]
Income Tax [Line Items]
Tax credit carryforwards, expiration date		Dec. 31, 2035