Supplementary Balance Sheet Information - Other Current Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Supplementary Balance Sheet Information
Deferred revenues	$ 50,378	$ 40,473
Accrued third-party commissions	31,763	28,310
Accrued expenses	30,008	32,861
Dividends payable	19,407	19,513
Litigation settlements	14,429	20,795
Accrued interest	18,974	19,029
Income taxes payable		1,673
Other	109,032	100,605
Total	$ 273,991	$ 263,259