Financial Instruments (Details) (USD $) In Thousands, unless otherwise specified	Aug. 02, 2011 3.75% Convertible Notes	Feb. 13, 2013 3.50% Convertible Notes	Jun. 30, 2013 Significant Other Observable Inputs (Level 2) 3.75% Convertible Notes	Jun. 30, 2013 Significant Other Observable Inputs (Level 2) 3.50% Convertible Notes	Jun. 30, 2013 Recurring basis Quoted Prices in Active Markets for Identical Instruments (Level 1)	Jun. 30, 2012 Recurring basis Quoted Prices in Active Markets for Identical Instruments (Level 1)	Jun. 30, 2013 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	Jun. 30, 2013 Recurring basis Quoted Prices in Active Markets for Identical Instruments (Level 1) Certificates of deposits Investments	Jun. 30, 2013 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	Jun. 30, 2013 Recurring basis Significant Other Observable Inputs (Level 2)	Jun. 30, 2013 Recurring basis Significant Other Observable Inputs (Level 2) Commercial paper	Jun. 30, 2013 Recurring basis Significant Other Observable Inputs (Level 2) Corporate notes	Jun. 30, 2013 Recurring basis Total balance	Jun. 30, 2012 Recurring basis Total balance	Jun. 30, 2013 Recurring basis Total balance Certificates of deposits	Jun. 30, 2012 Recurring basis Total balance Certificates of deposits	Jun. 30, 2013 Recurring basis Total balance Certificates of deposits Investments	Jun. 30, 2013 Recurring basis Total balance Money market funds	Jun. 30, 2012 Recurring basis Total balance Money market funds	Jun. 30, 2013 Recurring basis Total balance Commercial paper	Jun. 30, 2013 Recurring basis Total balance Corporate notes	Jun. 30, 2013 Non-recurring basis Significant Other Observable Inputs (Level 2)	Jun. 30, 2012 Non-recurring basis Significant Other Observable Inputs (Level 2)	Jun. 30, 2013 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	Jun. 30, 2013 Non-recurring basis Significant Other Observable Inputs (Level 2) 3.50% Convertible Notes	Jun. 30, 2013 Non-recurring basis Total balance	Jun. 30, 2012 Non-recurring basis Total balance	Jun. 30, 2013 Non-recurring basis Total balance 3.75% Convertible Notes	Jun. 30, 2012 Non-recurring basis Total balance 3.75% Convertible Notes	Jun. 30, 2013 Non-recurring basis Total balance 3.50% Convertible Notes
Fair value measurement
Fair value of assets					$ 15,838	$ 46,810	$ 15,365	$ 6,742	$ 2,600	$ 473	$ 40,068	$ 98,477	$ 3,992	$ 94,485	$ 114,315	$ 46,810	$ 15,365	$ 6,742	$ 2,600	$ 473	$ 40,068	$ 3,992	$ 94,485
Long term debt																								$ 240,862	$ 101,400	$ 96,560	$ 101,400	$ 144,302	$ 240,862	$ 101,400	$ 96,560	$ 101,400	$ 144,302
Interest rate (as a percent)	3.75%	3.50%	3.75%	3.50%