Going Concern - Additional Information (Detail) - USD ($) $ in Thousands	Apr. 05, 2017	Apr. 03, 2017	Apr. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016	Dec. 31, 2015	Dec. 22, 2015	Jul. 31, 2013
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Unrestricted cash and cash equivalents				$ 17,155	$ 21,524	$ 48,237	$ 185,606
Subsequent Event [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Special cash to be distributed	$ 140,000
Deposited into escrow account			$ 60,000
Convertible Notes [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Interest rate (as a percent)									4.50%
Convertible Notes [Member] | Subsequent Event [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Interest rate (as a percent)		4.50%
Deposited into escrow account		$ 60,000
2022 Notes [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Interest rate (as a percent)								11.50%
2022 Notes [Member] | Subsequent Event [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Interest rate (as a percent)		11.50%
Asset Sale Agreement [Member] | Convertible Notes [Member] | Subsequent Event [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Special cash to be distributed		$ 140,000
Asset Sale Agreement [Member] | 2022 Notes [Member] | Subsequent Event [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Aggregate principal amount outstanding to be redeemed		175,000
Additional premium payment		20,100
Ipsen [Member] | Asset Sale Agreement [Member] | Subsequent Event [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront cash payment received		$ 575,000