Senior and Subordinated Debt (Details Textuals) (USD $)	0 Months Ended	11 Months Ended		12 Months Ended				0 Months Ended	11 Months Ended					11 Months Ended					1 Months Ended		11 Months Ended	12 Months Ended								11 Months Ended			11 Months Ended			11 Months Ended							0 Months Ended	1 Months Ended		11 Months Ended	12 Months Ended
	Apr. 16, 2013	Dec. 31, 2013	Dec. 31, 2012	Jan. 31, 2013	Jan. 31, 2012	Jul. 12, 2013	Oct. 31, 2009 Puttable Equity Linked Senior Notes due 2011 [Member]	Apr. 16, 2013 Puttable Equity Linked Senior Notes due 2014 [Member]	Dec. 31, 2013 Puttable Equity Linked Senior Notes due 2014 [Member] D	Nov. 21, 2013 Puttable Equity Linked Senior Notes due 2014 [Member]	Jul. 12, 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]	Mar. 29, 2013 Senior Notes due 2015 [Member]	Jan. 31, 2013 Senior Notes due 2015 [Member]	Aug. 31, 2012 Senior Notes due 2015 [Member]	May 31, 2003 Senior Notes due 2015 [Member]	May 31, 2011 Convertible Senior Notes due 2016 [Member]	Jan. 31, 2011 Convertible Senior Notes due 2016 [Member]	Dec. 31, 2013 Convertible Senior Notes due 2016 [Member]	Jan. 31, 2012 Convertible Senior Notes due 2016 [Member]	Jan. 31, 2011 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]	Aug. 23, 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] D	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] D	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]	Oct. 15, 2013 Senior Notes due 2034 [Member]	Jan. 31, 2013 Senior Notes due 2034 [Member]	Aug. 31, 2012 Senior Notes due 2034 [Member]	Jul. 31, 2012 Senior Notes due 2034 [Member]	Feb. 29, 2004 Senior Notes due 2034 [Member]	May 31, 2003 Subordinated Debt [Member]	Apr. 16, 2013 Common Class A [Member]	May 31, 2011 Common Class A [Member]	Jan. 31, 2011 Common Class A [Member]	Dec. 31, 2013 Common Class A [Member]	Jan. 31, 2012 Common Class A [Member]	Jul. 12, 2013 Common Class A [Member]	Dec. 31, 2013 Minimum [Member] Senior Notes [Member]	Dec. 31, 2013 Maximum [Member] Senior Notes [Member]
Debt Instrument [Line Items]
Conversion price per share																					$ 13.91									$ 21.67			$ 24.21																$ 13.91	$ 24.21
Senior and subordinated debt, face amount							$ 167,433,000						$ 167,433,000					$ 300,000,000							$ 200,000,000				$ 150,000,000			$ 350,000,000		$ 300,000,000						$ 125,000,000	$ 100,000,000	$ 29,000,000
Interest rate							3.625%		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%	7.875%
Additional senior notes issued													32,567,000
Discount rate of senior notes issued													5.00%																											4.84%
Interest payable on notes									semi-annually on April 15 and October 15					semi-annually on December 1 and June 1							semi-annually on April 15 and October 15									semi-annually on February 15 and August 15			semi-annually on February 15 and August 15			quarterly on February 1, May 1, August 1 and November 1
Number of shares received by the note holder upon a put									68.7758																																							4,128,806
Principal amount of senior notes									1,000										1,000	1,000	1,000		1,000							1,000			1,000
Percentage of weighted average price of common stock equaled or exceeded put value price									130.00%
Minimum trading days during which daily volume weighted average price exceeds or equals put value price									20
Number consecutive trading days, convertible debt									30 days																					30 days			30 days
Senior notes exchanged for Class A common stock								138,853,000											40,000,000	110,000,000
Share of Class A common stock issued in exchange of debt																																											9,549,721	3,444,293	9,774,039	13,679,000	3,444,000
Cash payment for additional exchange consideration, accrued interest and in lieu of fractional shares	4,860,000
Loss on extinguishment of debt		4,549,000	6,807,000	7,096,000	9,590,000				(4,762,000)													(10,800,000)	(31,689,000)													(12,094,000)
Aggregate principal amount of senior notes put to the company											60,033,000
Cash payments for interest payable and in lieu of fractional shares for put transaction						1,088,000
Principal amount of notes redeemed										1,114,000					53,253,000		125,000,000										132,144,000										225,000,000
Number of common shares issued upon conversion of senior notes																			71.8894	71.8894	71.8894		71.8894							46.1425			41.3129													3.3
Increased number of shares issued in exchange of senior notes																			86.1073	88.8549			88.8549
Effective conversion price per share																					$ 16.37
Percentage of weighted average price of common stock equaled or exceeded conversion price																														130.00%			130.00%
Weighted average price of common stock equaled or exceeded conversion price																														$ 28.17			$ 31.47
Minimum trading days during which daily volume weighted average price exceeds or equals conversion price																														20			20
Minimum number of days after mailing conversion rights termination notice for effective termination date																														20 days			30 days
Net cash proceeds from issuance of convertible senior notes																																		291,250,000
Maximum number of days after mailing redemption notice for effective redemption date																																	60 days
Proceeds net of discounts and underwriters commissions																																								116,792,000
Cash deposited to be used to redeem debt																																								$ 8,208,000