Summary of Significant Accounting Policies (Narrative) (Details) (USD $)
3 Months Ended 12 Months Ended
Dec. 31, 2014
Sep. 30, 2014
Jun. 30, 2014
Mar. 31, 2014
Dec. 31, 2013
Sep. 30, 2013
Jun. 30, 2013
Mar. 31, 2013
Dec. 31, 2014
segment
Dec. 31, 2013
Dec. 31, 2012
Quantifying Misstatement in Current Year Financial Statements [Line Items]                      
Revenue $ 147,259,000 $ 162,654,000 $ 171,522,000 $ 157,270,000 $ 162,225,000 $ 182,768,000 $ 193,470,000 $ 212,986,000 $ 638,705,000 $ 751,449,000 $ 943,405,000
Operating income (loss) (10,826,000) 10,581,000 22,414,000 (7,858,000) (9,870,000) 19,524,000 19,133,000 39,676,000 14,311,000 68,463,000 191,627,000
Net income (5,248,000) 6,291,000 12,955,000 (4,330,000) (5,109,000) 14,211,000 12,114,000 24,667,000 9,668,000 45,883,000 121,146,000
Deferred compensation, maximum employee contribution, percentage of regular compensation                 80.00%    
Deferred compensation, maximum employee contribution, percentage of incentive compensation                 100.00%    
Deferred compensation, requisite service period                 4 years    
Company obligations under deferred compensation plan 1,000,000               1,000,000    
Advertising costs                 89,000,000 76,500,000 103,700,000
Number of reportable segments                 1    
Year-End Adjustment [Member]                      
Quantifying Misstatement in Current Year Financial Statements [Line Items]                      
Revenue (1,700,000)               (1,000,000)    
Operating income (loss) (1,700,000)               (700,000)    
Net income $ (1,000,000) $ 200,000             $ (200,000)