Income Taxes (Textuals) (Details) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Decrease in Unrecognized Tax Benefits is Reasonably Possible		$ 32,100,000
Tax Cuts and Jobs Act of 2017, Change in Tax Rate, Deferred Tax Asset, Income Tax Expense		4,500,000
Transition Tax obligation		2,800,000
SEC Schedule, 12-09, Valuation Allowances and Reserves, Amount		4,300,000
Deferred Tax Assets, Tax Credit Carryforwards, Foreign		0
Tax Cuts and Jobs Act of 2017, Incomplete Accounting, Provisional Income Tax Expense (Benefit)			$ 4,100,000
Decrease in current income tax payable			(1,400,000)
Increase (decrease) in deferred tax liabilities		(100,000)	900,000
Cumulative Effect on Retained Earnings, Net of Tax		(6,200,000)
Tax effected in state net operating loss carryforwards		600,000	800,000
Tax effected in foreign net operating loss carryforwards		12,600,000	$ 19,800,000
Valuation allowance related to federal capital loss carryforwards		9,000,000
Undistributed earnings of foreign subsidiaries		$ 27,100,000
Accounting Standards Update 2018-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative Effect on Retained Earnings, Net of Tax	$ 22,700,000
Accounting Standards Update 2016-16 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative Effect on Retained Earnings, Net of Tax	$ (5,100,000)