Debt (Details) (USD $)
3 Months Ended 6 Months Ended 6 Months Ended 3 Months Ended 6 Months Ended 6 Months Ended 6 Months Ended
Jun. 30, 2012
Jun. 30, 2011
Jun. 30, 2012
Jun. 30, 2011
Dec. 31, 2011
Jun. 30, 2012
Revolving Credit Facilities [Member]
Dec. 31, 2011
Revolving Credit Facilities [Member]
Sep. 30, 2011
Federal funds rate [Member]
Sep. 30, 2011
Margin rate [Member]
Sep. 30, 2011
LIBOR [Member]
Jun. 30, 2012
11.75% Senior Secured Notes due July 15, 2015 [Member]
Jun. 30, 2012
11.75% Senior Secured Notes due July 15, 2015 [Member]
Jul. 13, 2010
11.75% Senior Secured Notes due July 15, 2015 [Member]
Sep. 30, 2011
Tranche A [Member]
Jun. 30, 2012
Tranche A [Member]
Revolving Credit Facilities [Member]
Sep. 30, 2011
Tranche B [Member]
Jun. 30, 2012
Tranche B [Member]
Revolving Credit Facilities [Member]
Debt (Textual) [Abstract]                                  
Senior Secured Notes, face value           $ 100,000,000             $ 300,000,000 $ 20,000,000      
Senior secured notes, interest rate                     11.75% 11.75%          
Maturity date                       Jul. 15, 2015     Jul. 15, 2015   Apr. 15, 2015
Offering price                       99.077%          
Original issue discount                       2,800,000          
Net proceeds of acquisitions                       286,900,000          
Purchase of Senior Secured Notes                       101.00%          
Redemption of Initial Public Offer                       105,000,000          
Amounts outstanding                             30,000,000   70,000,000
Consolidated Secured Debt Ratio           3.50                      
Federal fund rate               0.50% 2.00% 3.00%       2.25%   3.25%  
Covenant     The Revolving Credit agreement contains customary financial and other covenants, including maximum consolidated leverage ratio of 4.50:1.00 and in certain instances 4.25:1.00. In addition, the Company is subject to covenants limiting incurrence of debt, liens on properties, investments, loans and advances, mergers and consolidations, asset sales, dividends and transactions with affiliates. The Company was in compliance with all required covenants as of June 30, 2012.                            
Amortized deferred loan fee 339,000 4,720,000 668,000 990,000             189,000,000 377,000,000          
Outstanding deferred loan fee 5,100,000   5,100,000   5,800,000 2,200,000 2,500,000                    
Debt (Additional Textual) [Abstract]                                  
Interest expense 5,700,000 8,800,000 11,500,000 17,600,000                          
Net of amortization 193,800,000   193,800,000   193,600,000                        
Amortization included in interest expense 81,000 109,000 160,000 215,000                          
Outstanding discounts $ 1,200,000   $ 1,200,000   $ 1,400,000