Subsequent Events (Details) (USD $)				0 Months Ended
	Jul. 25, 2014 Subsequent event Common stock	Jun. 30, 2014 Conversion of 2023 Notes	Jan. 31, 2013 Conversion of 2023 Notes	Jul. 15, 2014 Conversion of 2023 Notes Subsequent event	Jul. 15, 2014 Conversion of 2023 Notes Subsequent event Common stock
Subsequent events
Dividend declared (in dollars per share)	$ 0.25
Number of common shares issued upon debt conversion					1,519,367
Conversion price (in dollars per share)		$ 21.32	$ 27.79		$ 21.32
Number of common shares received upon partial debt conversion				149,645