Financing Receivables - Short-Term Payment Plans (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Short-term payment plans, net	$ 15,055	$ 5,459
Second Generation Meaningful Use Installment Plans, gross
Accounts, Notes, Loans and Financing Receivable [Line Items]
Short-term payment plans, gross	96	3,080
Fixed Periodic Payment Plans, gross
Accounts, Notes, Loans and Financing Receivable [Line Items]
Short-term payment plans, gross	8,985	1,988
Short-term payment plans, gross
Accounts, Notes, Loans and Financing Receivable [Line Items]
Short-term payment plans, gross	9,081	5,068
Less: allowance for losses	(638)	(1,796)
Less: unearned income	0	0
Short-term payment plans, net	$ 8,443	$ 3,272