Debt (Details Textual) (USD $)
3 Months Ended 0 Months Ended 12 Months Ended 0 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Mar. 20, 2013
Dec. 31, 2013
Nov. 15, 2013
Apr. 02, 2014
Oct. 23, 2014
Dec. 31, 2014
Debt [Line Items]                
Long-term Line of Credit, Noncurrent $ 19,602,000             $ 0
Interest Paid 367,000 334,000            
Letters of Credit Outstanding, Amount 4,803,000              
Accounts Payable, Total 40,044,000             72,147,000
6.75% Notes                
Debt [Line Items]                
Debt Instrument, Face Amount     550,000          
Debt instrument, stated interest rate 6.75%   6.75%          
Debt Instrument, Maturity Year     2020          
Debt Instrument, Maturity Date     Apr. 01, 2020          
Proceeds from Offering     537,600,000          
Debt Instrument, Redemption Date, One Apr. 01, 2016              
Debt Instrument, Redemption Date, Two Apr. 01, 2017              
Debt Instrument, Redemption Date, Latest For Redemption At Face Amount Apr. 01, 2018              
Debt Instrument, Percentage Of Redemption Price, Redemption Date One 103.375%              
Debt Instrument, Percentage Of Redemption Price, Redemption Date Two 101.688%              
Debt Instrument, Percentage Of Redemption Price, Redemption Date, Latest For Redemption At Face Amount 100.00%              
Debt Instrument, Percentage Redeemable Redemption Date, Additional 106.75%              
Debt Instrument, Percentage Of Redemption Price Redemption Date, Additional 35.00%              
Debt Instrument, Percentage Of Redemption Price, Change In Ownership Control 101.00%              
11% Notes                
Debt [Line Items]                
Debt instrument, stated interest rate     11.00%          
Loss on redemption of notes       55,588,000        
6.75% Notes issued in November 2013                
Debt [Line Items]                
Debt instrument, stated interest rate         6.75%      
Additional borrowing face amount         110,000,000      
Proceeds from Offering         111,925,000      
Debt Instrument, Unamortized Premium         4,125,000      
Expense Related to Distribution or Servicing and Underwriting Fees         2,200,000      
6.75% Notes Issued in April 2014                
Debt [Line Items]                
Debt instrument, stated interest rate           6.75%    
Additional borrowing face amount           75,000,000    
Proceeds from Offering           77,452,000    
Debt Instrument, Unamortized Premium           3,938,000    
Expense Related to Distribution or Servicing and Underwriting Fees           1,500,000    
Wells Fargo Capital Finance, LLC                
Debt [Line Items]                
Line of Credit Facility, Increase (Decrease), Net             100,000,000  
Long-term Line of Credit     225,000,000          
Debt Instrument, Maturity Date             Sep. 30, 2019  
Debt Instrument, Face Amount             $ 325,000,000  
Line of Credit Facility, Description     Dec. 31, 2018          
Wells Fargo Capital Finance, LLC | Base Rate                
Debt [Line Items]                
Debt instrument, stated interest rate 1.00%           1.00%  
Wells Fargo Capital Finance, LLC | London Interbank Offered Rate (LIBOR)                
Debt [Line Items]                
Debt instrument, stated interest rate 1.75%           1.75%