Stock-Based Compensation - Assumptions Used to Weighted-Average Grant Date Fair Values of Options Granted (Detail)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2015
Schedule Of Net Revenue Attributable To Medicaid Medicare Insurance And Self Pay As Percentage Of Net Air Medical Revenues [Line Items]
Risk free interest rate	1.64%
Expected term	4 years 9 months
Dividend yield	0.00%
Expected volatility	81.36%
Minimum [Member]
Schedule Of Net Revenue Attributable To Medicaid Medicare Insurance And Self Pay As Percentage Of Net Air Medical Revenues [Line Items]
Risk free interest rate		0.90%
Expected term		4 years 6 months 22 days
Dividend yield		0.00%
Expected volatility		76.76%
Maximum [Member]
Schedule Of Net Revenue Attributable To Medicaid Medicare Insurance And Self Pay As Percentage Of Net Air Medical Revenues [Line Items]
Risk free interest rate		1.47%
Expected term		7 years
Dividend yield		0.00%
Expected volatility		82.88%