Long-term Debt - Long-Term Debt (Parenthetical) (Detail)	Mar. 31, 2017
10% Senior Secured Toggle Notes due 2020
Debt Instrument [Line Items]
Interest rate on debt instrument	10.00%
7¾% Convertible Second Lien PIK Notes due 2019
Debt Instrument [Line Items]
Interest rate on debt instrument	7.75%
9½% Convertible Second Lien PIK Notes due 2020
Debt Instrument [Line Items]
Interest rate on debt instrument	9.50%
10% Senior Notes due 2020
Debt Instrument [Line Items]
Interest rate on debt instrument	10.00%
7¾% Senior Notes due 2019
Debt Instrument [Line Items]
Interest rate on debt instrument	7.75%
9½% Senior Notes due 2020
Debt Instrument [Line Items]
Interest rate on debt instrument	9.50%