Debtor in Possession - Condensed Statement of Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Condensed Cash Flow Statements, Captions [Line Items]
Net loss	$ (32,077)	$ (7,093)	$ (67,318)	$ (24,075)
Depreciation and amortization			38,775	38,598
Deferred income taxes			(7,407)	(7,446)
(Gain) loss on asset dispositions	(95)	(171)	(44)	708
Equity in (income) loss of unconsolidated affiliate, net	(1,039)	(81)	(2,400)	(45)
Inventory valuation reserves			1,416	3,308
Changes in operating assets and liabilities			13,301	(5,638)
Net cash (used in) provided by operating activities			(23,677)	5,410
Purchase of property and equipment			(8,970)	(18,098)
Proceeds from asset dispositions			1,235	1,453
Purchase of short-term investments			(183,421)	(260,996)
Proceeds from sale of short-term investments			121,512	264,918
Payment of deposit on aircraft			(50)	0
Refund of deposit on aircraft			503	0
Net cash used in investing activities			(69,191)	(12,997)
Debt issuance cost			(5,668)	0
Proceeds from Term Loan			70,000	0
Net cash provided by financing activities			64,332	4,669
Decrease in cash, cash equivalents and restricted cash			(29,019)	(2,918)
Cash, cash equivalents and restricted cash at the beginning of period			58,564	8,770
Cash, cash equivalents and restricted cash at end of period	29,545	$ 5,852	29,545	$ 5,852
Phi, Inc. and Debtors [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Net loss	(31,377)		(67,912)
Depreciation and amortization			29,799
Deferred income taxes			(6,492)
(Gain) loss on asset dispositions	(93)		(42)
Equity in (income) loss of unconsolidated affiliate, net	(1,039)		(2,400)
Inventory valuation reserves			1,110
Changes in operating assets and liabilities			19,751
Net cash (used in) provided by operating activities			(26,186)
Purchase of property and equipment			(7,817)
Proceeds from asset dispositions			1,235
Purchase of short-term investments			(183,421)
Proceeds from sale of short-term investments			121,512
Payment of deposit on aircraft			(50)
Refund of deposit on aircraft			503
Net cash used in investing activities			(68,038)
Debt issuance cost			(5,668)
Proceeds from Term Loan			70,000
Net cash provided by financing activities			64,332
Decrease in cash, cash equivalents and restricted cash			(29,892)
Cash, cash equivalents and restricted cash at the beginning of period			47,865
Cash, cash equivalents and restricted cash at end of period	$ 17,973		$ 17,973