Financial Instruments (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012 3.75% Convertible Notes	Aug. 02, 2011 3.75% Convertible Notes	Dec. 31, 2012 Recurring basis Quoted Prices in Active Markets for Identical Instruments (Level 1) Money market funds	Jun. 30, 2012 Recurring basis Quoted Prices in Active Markets for Identical Instruments (Level 1) Money market funds	Dec. 31, 2012 Recurring basis Quoted Prices in Active Markets for Identical Instruments (Level 1) Certificates of deposits	Jun. 30, 2012 Recurring basis Quoted Prices in Active Markets for Identical Instruments (Level 1) Certificates of deposits	Dec. 31, 2012 Recurring basis Total balance Money market funds	Jun. 30, 2012 Recurring basis Total balance Money market funds	Dec. 31, 2012 Recurring basis Total balance Certificates of deposits	Jun. 30, 2012 Recurring basis Total balance Certificates of deposits	Dec. 31, 2012 Non-recurring basis Significant Other Observable Inputs (Level 2) 3.75% Convertible Notes	Jun. 30, 2012 Non-recurring basis Significant Other Observable Inputs (Level 2) 3.75% Convertible Notes	Dec. 31, 2012 Non-recurring basis Total balance 3.75% Convertible Notes	Jun. 30, 2012 Non-recurring basis Total balance 3.75% Convertible Notes
Fair value measurement
Fair value of assets			$ 20,086	$ 40,068	$ 9,139	$ 6,742	$ 20,086	$ 40,068	$ 9,139	$ 6,742
Long term debt											$ 100,400	$ 101,400	$ 100,400	$ 101,400
Interest rate (as a percent)	3.75%	3.75%