Supplementary Balance Sheet Information - Other Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Supplementary Balance Sheet Information
Deferred revenues	$ 55,052	$ 40,473
Accrued expenses	33,553	32,861
Accrued third-party commissions	30,090	28,310
Dividends payable	25,118	19,513
Litigation settlements	14,333	20,795
Accrued interest	11,286	19,029
Income taxes payable	2,798	1,673
Other	122,069	100,605
Total	$ 294,299	$ 263,259