Subsequent Events - Additional Information (Detail)	Apr. 18, 2016 shares	Apr. 13, 2016 USD ($) shares	Jul. 31, 2013 USD ($)	Mar. 31, 2016 shares	Dec. 31, 2015 shares
Subsequent Event [Line Items]
Issuance of common stock | shares				116,411,000	115,871,000
Convertible Notes [Member]
Subsequent Event [Line Items]
Conversion ratio, principal amount			$ 1,000
Conversion rate of common stock shares per $1,000 principal amount			160
Subsequent Event [Member]
Subsequent Event [Line Items]
Conversion of aggregate principal amount		$ 64,200,000
Subsequent Event [Member] | Convertible Notes [Member]
Subsequent Event [Line Items]
Conversion of aggregate principal amount		64,200,000
Conversion ratio, principal amount		$ 1,000
Conversion rate of common stock shares per $1,000 principal amount	136
Issuance of common stock | shares	8,732,152	3,635,512
Value of additional shares issued for conversion		$ 27,700,000
Trading period		10 days