Other Assets - 2016 Loan to a Distribution Partner (Details) $ in Thousands	1 Months Ended	2 Months Ended	3 Months Ended	12 Months Ended
	Sep. 30, 2016 USD ($) renewal_option advance_period	Mar. 15, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Payments for notes issued				$ 3,073	$ 406	$ 755
Distribution Partner Two | Notes Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable, maximum available	$ 4,000
Number of loan advance periods | advance_period	2
Interest rate (percent)	6.00%		6.00%	6.00%
Note receivable			$ 3,000	$ 3,000
Number of renewal options | renewal_option	2
Renewal term (years)	1 year
Payments for notes issued			$ 3,000
LIBOR | Distribution Partner Two | Notes Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Basis spread on variable rate (percent)	4.00%
Subsequent Event | Distribution Partner Two | Notes Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest rate (percent)		6.00%
Payments for notes issued		$ 1,000