Procurement Contract and Research Agreements (Details)			1 Months Ended	3 Months Ended		6 Months Ended	12 Months Ended
	Jun. 24, 2011 course	May 13, 2011 USD ($) course	May 31, 2011 course	Jun. 30, 2017 USD ($) course	Mar. 31, 2017 USD ($)	Jun. 30, 2017 USD ($) course grant	Dec. 31, 2016 USD ($) course	Dec. 31, 2015 course	Dec. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2011 USD ($)
Procurement Contract [Line Items]
Contract value of various options		$ 122,700,000
Deferred costs				$ 83,190,032		$ 83,190,032	$ 72,649,277
Research and development revenue long-term contract				3,000,000		$ 7,600,000
Number of active grants | grant						1
Potential future research and development funding				$ 16,200,000		$ 16,200,000
Contract Value, Option, FDA Approval		50,000,000
Contract Value, Detail Of Option Exercisable, Development Activities		58,300,000
Contract Value, Detail Of Option Exercisable, Production Activities		14,400,000
Reduced holdback amount							40,900,000
Number of courses to be delivered by company | course				338,000		338,000
Amount of option to be received from BARDA for approval for extension of 84 moth expiry		50,000,000
Increase to funding of research and development contract					$ 10,100,000
BARDA Contract
Procurement Contract [Line Items]
Number of courses to be delivered | course			2,000,000			2,000,000
Value of contract		472,300,000
Contract Value of Manufacturing and Delivery Activities		409,800,000				$ 40,900,000
Contract value of development and support activities		$ 62,500,000
Number of courses under modified contract | course	1,700,000	1,700,000
Government contract, number of free courses | course		300,000
Proceeds from manufacture and physical delivery of courses, government contract				$ 368,900,000		368,900,000
Proceeds from advance payments under the BARDA contract											$ 41,000,000
Milestone payment				20,500,000					$ 8,200,000	$ 12,300,000
Proceeds From Physical Delivery Of Courses, Government Contracts									$ 286,900,000
Number of courses delivered and accepted at provisional dosage, once daily | course								1,300,000
Deferred costs				83,200,000		$ 83,200,000	$ 72,600,000
Government contract, total number of courses required to be delivered | course						2,000,000	2,000,000
Reduced holdback amount						$ 41,000,000
Deferred revenue				$ 376,500,000		$ 376,500,000