Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)	12 Months Ended			3 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Sep. 30, 2013 Aircraft	Jun. 30, 2013
Summary Of Significant Accounting Policies [Line Items]
Percentage of stock owned by CEO	69.50%
Maturities Period of liquid investments	Three months or less
Valuation reserves related to obsolescence and slow moving inventory	$ 13,500,000	$ 12,300,000
Insurance retention per claim	250,000
Accrued liabilities related to health care claims	1,700,000	1,500,000
Amount deductible per incident	500,000
Accrued expense related to workers compensation claims	2,500,000	2,900,000
Amounts paid to offshore insurance captive	900,000	800,000
Allowance for contractual discounts	96,600,000	74,700,000	54,600,000
Allowance for uncompensated care	41,900,000	46,400,000	48,000,000
Value of uncompensated care services	9,100,000	7,900,000	6,200,000
Estimated cost of providing charity services	2,100,000	3,000,000	2,200,000
Percentage of reserved category of self pay	100.00%
Contract termination period	90 days
Termination fee	13,500,000
Allowance for doubtful accounts	100,000	100,000
Percentage of consolidated operating revenues	30.00%	28.00%	28.00%
Percentage of trade receivables	18.00%	19.00%
Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Unrealized losses recorded	300,000
Medium Aircraft [Member]
Summary Of Significant Accounting Policies [Line Items]
Carrying value of aircraft	16,500,000	4,000,000
Market value of aircraft	6,000,000	2,400,000
Impairments of assets	10,500,000	1,600,000
Air Medical [Member]
Summary Of Significant Accounting Policies [Line Items]
Carrying value of aircraft	10,800,000
Cash realized from sale of assets	8,200,000
Gain or loss on sale of assets	2,600,000
Allowance for contractual discounts	96,600,000	74,700,000	54,600,000
Allowance for uncompensated care	41,900,000	46,400,000	48,000,000
Air Medical [Member] | Light Aircraft [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of aircraft sold	4
Air Medical [Member] | Medium Aircraft [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of aircraft sold	1
Number of Aircraft impaired	1	2
Oil and Gas [Member]
Summary Of Significant Accounting Policies [Line Items]
Carrying value of aircraft	5,500,000
Cash realized from sale of assets	5,900,000
Gain or loss on sale of assets	400,000
Oil and Gas [Member] | Light Aircraft [Member]
Summary Of Significant Accounting Policies [Line Items]
Carrying value of aircraft				1,200,000
Cash realized from sale of assets				2,600,000
Gain or loss on sale of assets				1,400,000
Number of aircraft sold	9			1
Oil and Gas [Member] | Fixed Wing Aircraft [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of aircraft sold	3
Oil and Gas [Member] | Medium Aircraft [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of Aircraft impaired	13	2
Oil and Gas [Member] | Heavy Aircraft [Member]
Summary Of Significant Accounting Policies [Line Items]
Carrying value of aircraft		20,600,000
Cash realized from sale of assets		37,000,000
Gain or loss on sale of assets		16,400,000
Number of aircraft sold		2
Air Medical and Technical Services [Member]
Summary Of Significant Accounting Policies [Line Items]
Percentage of consolidated operating revenues	10.00%	17.00%
Percentage of trade receivables	20.00%	20.00%
Aircraft [Member] | Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Salvage value of aircraft	54.00%
Aircraft [Member] | Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Salvage value of aircraft	25.00%
Flight equipment [Member] | Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life	15 years
Flight equipment [Member] | Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life	5 years
Other equipment [Member]
Summary Of Significant Accounting Policies [Line Items]
Gain or loss on sale of assets	1,400,000
Other equipment [Member] | Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life	10 years
Other equipment [Member] | Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life	3 years
Leasehold improvements [Member] | Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life	10 years
Leasehold improvements [Member] | Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life	6 years
Airframe [Member]
Summary Of Significant Accounting Policies [Line Items]
Gain or loss on sale of assets					$ 1,700,000