Income Taxes (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Line Items]
Unrecognized Tax Benefits	$ 0
Income tax payments	63,100,000	$ 70,200,000	$ 142,200,000
Income taxes payable	83,700,000	51,300,000
Income taxes receivable	49,300,000	64,300,000
One-time tax benefit as a result of the TCJA	5,699,000	339,899,000	0
Tax credit carryforwards	$ 39,877,000	48,938,000
Tax credit, expiration date	Dec. 31, 2028
Net operating loss carryforwards	$ 40,700,000
Estimated gross deferred tax assets including net operating losses realized through generating taxable income or reversal of existing temporary differences attributable to gross deferred tax liabilities	449,100,000
Valuation allowance	(36,286,000)	(25,225,000)
Change in Tax Status of UK Subsidiaries One-time Tax Expense	$ (103,281,000)	$ 0	$ 0
Earliest Tax Year [Member]
Income Tax Disclosure [Line Items]
Operating loss carryforwards, expiration date	Dec. 31, 2028
Latest Tax Year [Member]
Income Tax Disclosure [Line Items]
Operating loss carryforwards, expiration date	Dec. 31, 2037
Certain Branch Operations In Europe And Wholly Owned Subsidiary In Brazil [Member]
Income Tax Disclosure [Line Items]
Net operating loss carryforwards	$ 121,700,000
Certain Branch Operations In Europe And Wholly Owned Subsidiary In Brazil [Member] | Earliest Tax Year [Member]
Income Tax Disclosure [Line Items]
Operating loss carryforwards, expiration date	Dec. 31, 2020
Certain Branch Operations In Europe And Wholly Owned Subsidiary In Brazil [Member] | Latest Tax Year [Member]
Income Tax Disclosure [Line Items]
Operating loss carryforwards, expiration date	Dec. 31, 2027
Certain Branch Operations In Europe And Wholly Owned Subsidiary In Brazil [Member] | Subject To Expiration [Member]
Income Tax Disclosure [Line Items]
Net operating loss carryforwards	$ 31,400,000