Revenue - Assets Recognized for Costs to Obtain a Contract with a Customer (Details)	Dec. 31, 2020
Capitalized commission fees | Minimum
Assets Recognized for Costs to Obtain a Contract with a Customer
Amortization period	2 years
Capitalized commission fees | Maximum
Assets Recognized for Costs to Obtain a Contract with a Customer
Amortization period	10 years
Capitalized transmitter costs | Minimum
Assets Recognized for Costs to Obtain a Contract with a Customer
Amortization period	8 years
Capitalized transmitter costs | Maximum
Assets Recognized for Costs to Obtain a Contract with a Customer
Amortization period	10 years