Long-Lived Assets - Summary of Aggregate Amortization Related to Client Contract Costs (Parenthetical) (Details)	12 Months Ended
	Dec. 31, 2019
Minimum | Client contract incentives
Finite Lived Intangible Assets [Line Items]
Intangible assets, amortization year	2023
Minimum | Capitalized costs
Finite Lived Intangible Assets [Line Items]
Intangible assets, amortization year	2020
Minimum | Capitalized commission fees
Finite Lived Intangible Assets [Line Items]
Intangible assets, amortization year	2020
Maximum | Client contract incentives
Finite Lived Intangible Assets [Line Items]
Intangible assets, amortization year	2025
Maximum | Capitalized costs
Finite Lived Intangible Assets [Line Items]
Intangible assets, amortization year	2028
Maximum | Capitalized commission fees
Finite Lived Intangible Assets [Line Items]
Intangible assets, amortization year	2026
Policy election to expense fees as incurred	1 year