Restructuring - Additional Information (Detail) - Jun. 30, 2015	USD ($) NonExecutiveOfficers	USD ($) NonExecutiveOfficers Employees
Restructuring Cost and Reserve [Line Items]
Additional cost of goods sold related to inventory		$ 1,229,000
Prepayments to supplier for lower housing assembly	$ 1,024,000	$ 1,024,000
Severance payment description		Each affected employee will receive (i) severance payments equal to three months of salary plus an additional amount equal to one week of salary for each year of Alexza service in excess of five years; and (ii) three months of paid medical insurance premiums and outplacement services, or in total, the Severance Package.
Number of non-executive officers | NonExecutiveOfficers	2	2
Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Aggregate cost of severance package	$ 203,000	$ 203,000
Number of employees eliminated | Employees		6
Number of employees planned to be eliminated | Employees		22
Severance package cost	248,000	$ 738,000
Employee Severance [Member] | If Employees Position Is Not Eliminated [Member]
Restructuring Cost and Reserve [Line Items]
Severance package cost	$ 384,000	$ 1,417,000