Description of Business and Significant Accounting Policies (Details)	9 Months Ended
	Sep. 30, 2017 financial_institution segment	Dec. 31, 2016 financial_institution
Schedule of Accounting Policies [Line Items]
Service term	1 year
Number of reportable segments | segment	2
Amortization period of inventories and supplies	24 months
Number of financial institutions holding cash and cash equivalents and marketable securities | financial_institution	1	1
Minimum
Schedule of Accounting Policies [Line Items]
Days to notify cancellation of service	30 days
Initial period of service term	60 days
Maximum
Schedule of Accounting Policies [Line Items]
Days to notify cancellation of service	90 days
Initial period of service term	120 days