Summary of Significant Accounting Policies - Goodwill (Details)	3 Months Ended	12 Months Ended
Dec. 31, 2019 USD ($) Reporting_Unit	Dec. 31, 2019 USD ($) Divisions	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($) Reporting_Unit	Dec. 31, 2016 USD ($)
Accounting Policies [Abstract]
Number of internal divisions \| Divisions		2
Non-cash charge for impairment of goodwill	$ 0		$ 0	$ 57,011,000
Number of reporting units \| Reporting_Unit	1			2
Decrease in fair value of reporting units considered for impairment calculation	10.00%	10.00%
Goodwill	$ 2,022,675,000	$ 2,022,675,000	$ 1,899,879,000	$ 1,868,600,000	$ 1,603,169,000

Decrease in fair value of Reporting units considered, for impairment calculation.

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Number of internal divisions.

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- Definition

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
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Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Number of reporting units tested for impairment of goodwill. A reporting unit is an operating segment or one level below an operating segment.

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