v3.7.0.1
Condensed Consolidating Financial Information - Guarantor Subsidiaries - Condensed Consolidating Statements of Cash Flows (Detail) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2017
Jun. 30, 2016
Jun. 30, 2017
Jun. 30, 2016
Condensed Cash Flow Statements, Captions [Line Items]        
Net cash (used in) provided by operating activities $ (7,949) $ 799 $ (7,949) $ 799
Investing activities:        
Purchase of property and equipment (43,892) (39,908) (43,892) (39,908)
Proceeds from asset dispositions 17 10,998 17 10,998
Purchase of short-term investments (134,518) (151,436) (134,518) (151,436)
Proceeds from sale of short-term investments 187,217 148,838 187,217 148,838
Payments of deposits on aircraft (110) (131) (110) (131)
Net cash provided by (used in) investing activities 8,714 (31,639) 8,714 (31,639)
Financing activities:        
Proceeds from line of credit 66,525 150,800 66,525 150,800
Payments on line of credit (67,300) (113,300) (67,300) (113,300)
Repurchase of common stock (263) (500) (263) (500)
Net cash (used in) provided by financing activities (1,038) 37,000 (1,038) 37,000
Increase (decrease) in cash (273) 6,160 (273) 6,160
Cash, beginning of period     2,596 2,407
Cash, end of period 2,323 8,567 2,323 8,567
Parent Company Only (issuer) [Member]        
Condensed Cash Flow Statements, Captions [Line Items]        
Net cash (used in) provided by operating activities (34,236) (12,954)    
Investing activities:        
Purchase of property and equipment (43,892) (39,535)    
Proceeds from asset dispositions 17 10,998    
Purchase of short-term investments (134,518) (151,436)    
Proceeds from sale of short-term investments 187,217 148,838    
Payments of deposits on aircraft (110) (131)    
Net cash provided by (used in) investing activities 8,714 (31,266)    
Financing activities:        
Proceeds from line of credit 66,525 150,800    
Payments on line of credit (67,300) (113,300)    
Repurchase of common stock (263) (500)    
Due to/from affiliate, net 26,572 7,214    
Net cash (used in) provided by financing activities 25,534 44,214    
Increase (decrease) in cash 12 (6)    
Cash, beginning of period     36 46
Cash, end of period 48 40 48 40
Guarantor Subsidiaries [Member]        
Condensed Cash Flow Statements, Captions [Line Items]        
Net cash (used in) provided by operating activities 18,916 13,753    
Investing activities:        
Purchase of property and equipment 0 (373)    
Net cash provided by (used in) investing activities 0 (373)    
Financing activities:        
Due to/from affiliate, net (19,688) (7,214)    
Net cash (used in) provided by financing activities (19,688) (7,214)    
Increase (decrease) in cash (772) 6,166    
Cash, beginning of period     2,100 2,361
Cash, end of period 1,328 $ 8,527 1,328 $ 8,527
Non-Guarantor Subsidiaries [Member]        
Condensed Cash Flow Statements, Captions [Line Items]        
Net cash (used in) provided by operating activities 7,371      
Investing activities:        
Net cash provided by (used in) investing activities 0      
Financing activities:        
Due to/from affiliate, net (6,884)      
Net cash (used in) provided by financing activities (6,884)      
Increase (decrease) in cash 487      
Cash, beginning of period     460  
Cash, end of period $ 947   $ 947