Long-Lived Assets - Summary of Aggregate Amortization Related to Intangible Assets (Parenthetical) (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Acquired client contracts
Finite Lived Intangible Assets [Line Items]
Estimated useful life		109 months
Acquired client contracts | Minimum
Finite Lived Intangible Assets [Line Items]
Estimated useful life	2 years
Acquired client contracts | Maximum
Finite Lived Intangible Assets [Line Items]
Estimated useful life	20 years
Acquired software | Minimum
Finite Lived Intangible Assets [Line Items]
Estimated useful life	2 years
Acquired software | Maximum
Finite Lived Intangible Assets [Line Items]
Estimated useful life	15 years
Internal use software | Minimum
Finite Lived Intangible Assets [Line Items]
Estimated useful life	12 months
Internal use software | Maximum
Finite Lived Intangible Assets [Line Items]
Estimated useful life	10 years