v3.3.1.900
Condensed Consolidating Financial Information - Guarantor Subsidiaries - Condensed Consolidating Balance Sheets (Detail) - USD ($)
$ in Thousands
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Current Assets:        
Cash $ 2,407 $ 6,270 $ 934 $ 2,849
Short-term investments 284,523 185,244    
Accounts receivable - net 144,778 180,761    
Inventories of spare parts - net 69,491 73,793    
Prepaid expenses 8,951 9,314    
Deferred income taxes 10,379 9,915    
Income taxes receivable 761 1,227    
Total current assets 521,290 466,524    
Property and equipment, net 883,529 877,818    
Restricted investments 15,336 15,485    
Other assets 10,177 16,253    
Total assets 1,430,332 1,376,080    
Current Liabilities:        
Accounts payable 31,373 27,700    
Accrued and other current liabilities 44,759 52,812    
Total current liabilities 76,132 80,512    
Long-term debt 557,500 543,000    
Deferred income taxes and other long-term liabilities 169,702 155,500    
Shareholders' Equity:        
Common stock and paid-in capital 306,444 303,082    
Accumulated other comprehensive loss (567) (211)    
Retained earnings 321,121 294,197    
Total shareholders' equity 626,998 597,068 559,965 499,615
Total liabilities and shareholders' equity 1,430,332 1,376,080    
Parent Company Only (issuer) [Member]        
Current Assets:        
Cash 46 51 52 552
Short-term investments 284,523 185,244    
Accounts receivable - net 70,336 98,001    
Inventories of spare parts - net 60,060 65,341    
Prepaid expenses 7,162 7,610    
Deferred income taxes 10,379 9,915    
Income taxes receivable 1,002 1,068    
Total current assets 433,508 367,230    
Investment in subsidiaries 330,848 358,080    
Property and equipment, net 632,759 638,437    
Restricted investments 15,336 15,485    
Other assets 9,974 16,055    
Total assets 1,422,425 1,395,287    
Current Liabilities:        
Accounts payable 25,512 22,578    
Accrued and other current liabilities 29,138 34,477    
Intercompany payable 90,943 95,270    
Total current liabilities 145,593 152,325    
Long-term debt 557,500 543,000    
Deferred income taxes and other long-term liabilities 92,334 102,894    
Shareholders' Equity:        
Common stock and paid-in capital 306,444 303,082    
Accumulated other comprehensive loss (567) (211)    
Retained earnings 321,121 294,197    
Total shareholders' equity 626,998 597,068    
Total liabilities and shareholders' equity 1,422,425 1,395,287    
Guarantor Subsidiaries [Member]        
Current Assets:        
Cash [1] 2,361 6,219 $ 882 [2] $ 2,297 [2]
Accounts receivable - net [1] 74,442 82,760    
Intercompany receivable [1] 90,943 95,399    
Inventories of spare parts - net [1] 9,431 8,452    
Prepaid expenses [1] 1,789 1,704    
Income taxes receivable [1] (241) 159    
Total current assets [1] 178,725 194,693    
Property and equipment, net [1] 250,770 239,381    
Other assets [1] 203 198    
Total assets [1] 429,698 434,272    
Current Liabilities:        
Accounts payable [1] 5,861 5,122    
Accrued and other current liabilities [1] 15,621 18,335    
Total current liabilities [1] 21,482 23,457    
Deferred income taxes and other long-term liabilities [1] 77,368 52,606    
Shareholders' Equity:        
Common stock and paid-in capital [1] 79,061 137,647    
Retained earnings [1] 251,787 220,562    
Total shareholders' equity [1] 330,848 358,209    
Total liabilities and shareholders' equity [1] 429,698 434,272    
Eliminations [Member]        
Current Assets:        
Intercompany receivable (90,943) (95,399)    
Total current assets (90,943) (95,399)    
Investment in subsidiaries (330,848) (358,080)    
Total assets (421,791) (453,479)    
Current Liabilities:        
Intercompany payable (90,943) (95,270)    
Total current liabilities (90,943) (95,270)    
Shareholders' Equity:        
Common stock and paid-in capital (79,061) (137,647)    
Retained earnings (251,787) (220,562)    
Total shareholders' equity (330,848) (358,209)    
Total liabilities and shareholders' equity $ (421,791) $ (453,479)    
[1] Foreign subsidiaries represent minor subsidiaries and are included in the guarantor subsidiaries' amounts.
[2] Cash flows between the Parent Company and guarantor subsidiaries related to the Company's centralized cash management activities in 2013 have been adjusted to show the effects on net cash provided by operating and financing activities.