Income Taxes - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2014 USD ($)
Income Taxes [Line Items]
Percentage of common stock ownership under transfer restriction	4.90%
Federal
Income Taxes [Line Items]
Net operating loss carry forwards	$ 933.6
Net operating loss expiration period	20 years
Net operating loss carry forwards expiration year	Dec. 31, 2027
California
Income Taxes [Line Items]
Net operating loss carry forwards	$ 994.7
Net operating loss carry forwards expiration year	Dec. 31, 2017
Minimum | California
Income Taxes [Line Items]
Net operating loss expiration period	10 years
Maximum | California
Income Taxes [Line Items]
Net operating loss expiration period	20 years