Senior and Subordinated Debt Senior and Subordinated Debt (Details Textuals) (USD $)	1 Months Ended	3 Months Ended			1 Months Ended		1 Months Ended	3 Months Ended		1 Months Ended
	Apr. 30, 2013	Apr. 30, 2013	Apr. 30, 2012	Apr. 30, 2013 Puttable Equity-Linked Senior Notes due 2014 [Member]	Apr. 30, 2013 Puttable Equity-Linked Senior Notes due 2014 [Member]	Mar. 29, 2013 Senior Notes due 2015 [Member]	Apr. 30, 2013 Common Class A [Member]	Apr. 30, 2013 Common Class A [Member]	May 31, 2013 Subsequent Event [Member] Puttable Equity-Linked Senior Notes due 2014 [Member]	Jun. 20, 2013 Subsequent Event [Member] Common Class A [Member]
Debt Instrument [Line Items]
Repayment of debt issuing Class A common stock					$ 138,853,000
Issuance of Class A shares in exchange for Puttable Equity-Linked Senior Notes due 2014, Shares							9,549,721	9,550,000
Cash payment for additional exchange consideration, accrued interest and in lieu of fractional shares	4,860,000
Loss on extinguishment of debt		5,238,000	719,000	4,762,000
Number of Shares Received by the Note Holder upon a Put										68.7758
Principal Amount of Notes									1,000
Aggregate principal amount outstanding									61,147,000
Principal amount of notes redeemed						$ 53,253,000