Basis of Presentation and Accounting Policies - Additional Information (Details) € in Millions	1 Months Ended		3 Months Ended			6 Months Ended	9 Months Ended
	Apr. 30, 2019 USD ($)	Apr. 30, 2019 EUR (€)	Sep. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)
Accounting Policies [Line Items]
Net proceeds from sale of tax credits	$ 103,500,000	€ 92.0
Non-cash impairment charge loss			$ 0				$ 66,800,000	$ 64,000,000.0
Percentage of consolidated goodwill balance			80.00%				80.00%
Goodwill			$ 1,198,600,000				$ 1,198,600,000		$ 1,260,100,000
Minimum
Accounting Policies [Line Items]
Percentage of goodwill over fair value of reporting unit			20.00%
Other Reporting Units | Minimum
Accounting Policies [Line Items]
Percentage of goodwill over fair value of reporting unit			10.00%
Germany
Accounting Policies [Line Items]
Non-cash impairment charge loss				$ 66,800,000	$ 60,200,000
United Kingdom
Accounting Policies [Line Items]
Percentage of goodwill over fair value of reporting unit			12.00%
United Kingdom | Discount Rates
Accounting Policies [Line Items]
Discount rate for goodwill impairment test (as a percent)			11.5				11.5
United Kingdom | Terminal Value Revenue Growth Rate
Accounting Policies [Line Items]
Discount rate for goodwill impairment test (as a percent)			1.0				1.0
United Kingdom | Terminal Value OUP Margin
Accounting Policies [Line Items]
Discount rate for goodwill impairment test (as a percent)			3.1				3.1
Netherlands
Accounting Policies [Line Items]
Percentage of goodwill over fair value of reporting unit			3.30%
Goodwill			$ 114,500,000				$ 114,500,000
Netherlands | Maximum
Accounting Policies [Line Items]
Percentage of goodwill over fair value of reporting unit			10.00%
Netherlands | Discount Rates
Accounting Policies [Line Items]
Discount rate for goodwill impairment test (as a percent)			10.9				10.9
Netherlands | Terminal Value Revenue Growth Rate
Accounting Policies [Line Items]
Discount rate for goodwill impairment test (as a percent)			2.0				2.0
Netherlands | Terminal Value OUP Margin
Accounting Policies [Line Items]
Discount rate for goodwill impairment test (as a percent)			3.5				3.5
Northern Europe | Germany
Accounting Policies [Line Items]
Goodwill									67,200,000
Northern Europe | United Kingdom
Accounting Policies [Line Items]
Goodwill			$ 94,700,000				$ 94,700,000		97,300,000
Northern Europe | Netherlands
Accounting Policies [Line Items]
Goodwill			$ 114,500,000				$ 114,500,000		$ 109,500,000
Northern Europe | Germany
Accounting Policies [Line Items]
Non-cash impairment charge loss						$ 66,800,000