Supplemental Guarantor Information (Details 3) (USD $)
3 Months Ended
Mar. 31, 2015
Mar. 31, 2014
CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME    
Net income $ 26,457,000 $ 23,527,000
Other comprehensive income, net:    
Amortization of actuarial loss on defined benefit pension plan, net 68,000 5,000
Unrealized (loss) gain on marketable securities, available-for-sale, net (19,000) 188,000
Other comprehensive income, net 49,000 193,000
Comprehensive income 26,506,000 23,720,000
CONSOLIDATING ELIMINATIONS    
CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME    
Net income (14,515,000) (9,823,000)
Other comprehensive income, net:    
Amortization of actuarial loss on defined benefit pension plan, net 0  
Unrealized (loss) gain on marketable securities, available-for-sale, net 0  
Other comprehensive income, net 0  
Comprehensive income (14,515,000) (9,823,000)
TRG, INC. | Reportable legal entities    
CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME    
Net income 26,457,000 23,527,000
Other comprehensive income, net:    
Amortization of actuarial loss on defined benefit pension plan, net 47,000 5,000
Unrealized (loss) gain on marketable securities, available-for-sale, net (19,000) 188,000
Other comprehensive income, net 28,000 193,000
Comprehensive income 26,485,000 23,720,000
GUARANTOR SUBSIDIARIES | Reportable legal entities    
CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME    
Net income 11,237,000 10,693,000
Other comprehensive income, net:    
Amortization of actuarial loss on defined benefit pension plan, net 16,000  
Unrealized (loss) gain on marketable securities, available-for-sale, net 0  
Other comprehensive income, net 16,000  
Comprehensive income 11,253,000 10,693,000
NON-GUARANTOR SUBSIDIARIES | Reportable legal entities    
CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME    
Net income 3,278,000 (870,000)
Other comprehensive income, net:    
Amortization of actuarial loss on defined benefit pension plan, net 5,000  
Unrealized (loss) gain on marketable securities, available-for-sale, net 0  
Other comprehensive income, net 5,000  
Comprehensive income $ 3,283,000 $ (870,000)