Income Taxes (Narrative) (Details) - USD ($)	1 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Components of Income Tax Expense (Benefit), Continuing Operations [Abstract]
Income tax expense (benefit)		$ (7,400,000)
Provisional reduction to AMT credit		6.60%
AMT credit carryforward	$ 57,900,000	$ 57,900,000	$ 47,200,000
Net decrease of unrecognized tax benefits		(3,300,000)
Tax settlement paid	4,600,000
Unrecognized tax benefits that would impact effective tax rate	10,100,000	10,100,000	11,800,000
Interest and penalty expense, excluding refunds		(1,104,000)	606,000	$ 112,000
Accrued interest and penalty	$ 2,417,000	$ 2,417,000	$ 3,521,000