Fair Value of Assets and Liabilities (Details 2) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Jun. 30, 2011	Dec. 31, 2010
Fair Value of Assets and Liabilities
Financial liabilities	$ 2,120,883
Unamortized discounts	(5,169)	(5,169)	(8,043)
Mortgage note, due 2011 at 8.3%
Fair Value of Assets and Liabilities
Interest rate stated percentage	8.30%		8.30%
Senior Notes, due 2012 at 6.85%
Fair Value of Assets and Liabilities
Financial liabilities	100,829		100,829
Interest rate stated percentage	6.85%		6.85%
Senior Notes, due 2013 at 6.75%
Fair Value of Assets and Liabilities
Financial liabilities	287,000		287,000
Interest rate stated percentage	6.75%		6.75%
Senior Notes, due 2014 at 7.875%
Fair Value of Assets and Liabilities
Financial liabilities	300,000		300,000
Interest rate stated percentage	7.875%		7.875%
Senior Notes, due 2015 at 5.125%
Fair Value of Assets and Liabilities
Financial liabilities	280,000		280,000
Interest rate stated percentage	5.125%		5.125%
Senior Notes, due 2016 at 6.3%
Fair Value of Assets and Liabilities
Financial liabilities	275,000		275,000
Interest rate stated percentage	6.30%		6.30%
Senior Notes, due 2017 at 5.625%
Fair Value of Assets and Liabilities
Financial liabilities	300,000		300,000
Interest rate stated percentage	5.625%		5.625%
Senior Notes, due 2018 at 6.7%
Fair Value of Assets and Liabilities
Financial liabilities	350,000		350,000
Interest rate stated percentage	6.70%		6.70%
Convertible senior notes, due 2027 at 3.8%
Fair Value of Assets and Liabilities
Financial liabilities	79,054		79,054
Unamortized discounts	231		1,570
Interest rate stated percentage	3.80%		3.80%
Carrying Amount
Fair Value of Assets and Liabilities
Unamortized discounts	(5,169)		(8,043)
Financial liabilities	1,966,714		1,967,223
Carrying Amount | Mortgage note, due 2011 at 8.3%
Fair Value of Assets and Liabilities
Financial liabilities			3,383
Carrying Amount | Senior Notes, due 2012 at 6.85%
Fair Value of Assets and Liabilities
Financial liabilities	100,829		100,829
Carrying Amount | Senior Notes, due 2013 at 6.75%
Fair Value of Assets and Liabilities
Financial liabilities	287,000		287,000
Carrying Amount | Senior Notes, due 2014 at 7.875%
Fair Value of Assets and Liabilities
Financial liabilities	300,000		300,000
Carrying Amount | Senior Notes, due 2015 at 5.125%
Fair Value of Assets and Liabilities
Financial liabilities	280,000		280,000
Carrying Amount | Senior Notes, due 2016 at 6.3%
Fair Value of Assets and Liabilities
Financial liabilities	275,000		275,000
Carrying Amount | Senior Notes, due 2017 at 5.625%
Fair Value of Assets and Liabilities
Financial liabilities	300,000		300,000
Carrying Amount | Senior Notes, due 2018 at 6.7%
Fair Value of Assets and Liabilities
Financial liabilities	350,000		350,000
Carrying Amount | Convertible senior notes, due 2027 at 3.8%
Fair Value of Assets and Liabilities
Financial liabilities	79,054		79,054
Fair Value
Fair Value of Assets and Liabilities
Financial liabilities	2,102,924		2,163,948
Fair Value | Mortgage note, due 2011 at 8.3%
Fair Value of Assets and Liabilities
Financial liabilities			3,408
Fair Value | Senior Notes, due 2012 at 6.85%
Fair Value of Assets and Liabilities
Financial liabilities	105,407		109,897
Fair Value | Senior Notes, due 2013 at 6.75%
Fair Value of Assets and Liabilities
Financial liabilities	301,871		315,364
Fair Value | Senior Notes, due 2014 at 7.875%
Fair Value of Assets and Liabilities
Financial liabilities	333,887		349,974
Fair Value | Senior Notes, due 2015 at 5.125%
Fair Value of Assets and Liabilities
Financial liabilities	290,052		296,782
Fair Value | Senior Notes, due 2016 at 6.3%
Fair Value of Assets and Liabilities
Financial liabilities	291,572		297,795
Fair Value | Senior Notes, due 2017 at 5.625%
Fair Value of Assets and Liabilities
Financial liabilities	313,106		316,846
Fair Value | Senior Notes, due 2018 at 6.7%
Fair Value of Assets and Liabilities
Financial liabilities	386,942		392,303
Fair Value | Convertible senior notes, due 2027 at 3.8%
Fair Value of Assets and Liabilities
Financial liabilities	$ 80,087		$ 81,579