Quarterly Data (Unaudited) (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Pension settlement charges	$ 41,406	$ 0	$ 120
Tax Cuts and Jobs Act of 2017, Incomplete Accounting, Provisional Income Tax Expense (Benefit)		$ 17,100
TCJA Tax Benefit	$ (11,100)