Debt (Details 2) (USD $)	3 Months Ended
	Jun. 30, 2011	Mar. 31, 2011
Debt
Loss on extinguishment of debt		$ 304,000
Convertible Notes
Debt
Conversion price of convertible notes (in dollars per share)	$ 50.59	$ 45.95
Principal of notes tendered for conversion		7,500,000
Notes tendered, cash paid	98,100,000	7,500,000
Notes tendered, shares issued upon conversion	1,660,095	111,318
Loss on extinguishment of debt	$ 3,000,000	$ 300,000