Senior and Subordinated Debt (Details) (USD $)	Dec. 31, 2013	Jan. 31, 2013	Dec. 31, 2013 Puttable Equity Linked Senior Notes due 2014 [Member]	Jan. 31, 2013 Puttable Equity Linked Senior Notes due 2014 [Member]	Oct. 31, 2009 Puttable Equity Linked Senior Notes due 2014 [Member]	Dec. 31, 2013 Senior Notes due 2015 [Member]	Jan. 31, 2013 Senior Notes due 2015 [Member]	May 31, 2003 Senior Notes due 2015 [Member]	Dec. 31, 2013 Convertible Senior Notes due 2016 [Member]	Jan. 31, 2013 Convertible Senior Notes due 2016 [Member]	Oct. 31, 2009 Convertible Senior Notes due 2016 [Member]	Dec. 31, 2013 Senior Notes Due 2017 [Member]	Jan. 31, 2013 Senior Notes Due 2017 [Member]	Jan. 31, 2005 Senior Notes Due 2017 [Member]	Dec. 31, 2013 Convertible Senior Notes due 2018 [Member]	Jan. 31, 2013 Convertible Senior Notes due 2018 [Member]	Jul. 31, 2011 Convertible Senior Notes due 2018 [Member]	Dec. 31, 2013 Convertible Senior Notes due 2020 [Member]	Jul. 31, 2013 Convertible Senior Notes due 2020 [Member]	Jan. 31, 2013 Convertible Senior Notes due 2020 [Member]	Dec. 31, 2013 Senior Notes due 2034 [Member]	Jan. 31, 2013 Senior Notes due 2034 [Member]	Aug. 31, 2012 Senior Notes due 2034 [Member]	Feb. 29, 2004 Senior Notes due 2034 [Member]	Dec. 31, 2013 Subordinate Tax Revenue Bonds due 2013 [Member]	Jan. 31, 2013 Subordinate Tax Revenue Bonds due 2013 [Member]
Debt Instrument [Line Items]
Interest Rate			3.625%	3.625%	3.625%	7.625%	7.625%	7.625%	5.00%	5.00%	5.00%	6.50%	6.50%	6.50%	4.25%	4.25%	4.25%	3.625%	3.625%	3.625%	7.375%	7.375%	7.375%	7.375%
Senior Notes
Senior Notes	$ 700,000,000	$ 1,003,969,000	$ 0	$ 199,457,000		$ 0	$ 53,253,000		$ 50,000,000	$ 50,000,000		$ 0	$ 132,144,000		$ 350,000,000	$ 350,000,000		$ 300,000,000		$ 0	$ 0	$ 219,115,000
Subordinated Debt [Abstract]
Subordinate Tax Revenue Bonds due 2013																									0	29,000,000
Senior and Subordinated debt	$ 700,000,000	$ 1,032,969,000