Income Taxes Income Taxes - Narrative (Details) - USD ($)	12 Months Ended			13 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Jun. 30, 2017
Tax Credit Carryforward [Line Items]
Effective income tax rate (as a percent)	16.70%	9.50%	12.40%
Provisional income tax expense (benefit)			$ 6,500,000	$ 6,600,000
Change in tax rate effect on deferred taxes			10,300,000	11,200,000
Transition tax for accumulated foreign earnings, income tax expense (benefit)			3,800,000	$ 4,600,000
Measurement period tax benefit adjustment		$ 900,000
Measurement period adjustment to transition tax		800,000
Measurement period adjustment			8,100,000
Change in statutory tax rate, amount	$ 0	$ (1,600,000)	(9,700,000)
Deferred income tax benefit			1,600,000
Transition tax for accumulated foreign earnings			2,200,000
Retained Earnings
Tax Credit Carryforward [Line Items]
Reclassification of the unrealized loss on available-for-sale securities (Note 10)			10,900,000
Federal Ministry of Finance, Germany
Tax Credit Carryforward [Line Items]
Elimination of foreign earnings repatriated			4,100,000		$ 4,100,000
Change in statutory tax rate, amount			$ 600,000