Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Line Items]
Cash paid for income taxes	$ 800,000	$ 500,000	$ 800,000
Deferred tax assets, valuation allowance	$ 2,762,000	$ 2,762,000
Income tax rate at federal statutory rates	21.00%	35.00%	35.00%
Charitable Contribution Carryforwards [Member]
Income Tax Disclosure [Line Items]
Deferred tax assets, valuation allowance		$ 400,000
Minimum [Member]
Income Tax Disclosure [Line Items]
Year federal net operating loss carryforwards begin to expire	2029
Ownership shift as defined by IRC Section 382		50.00%
Federal Tax Credit Carry Forwards [Member]
Income Tax Disclosure [Line Items]
Net operating loss carryforwards	$ 615,300,000
State Tax Credit Carry Forwards [Member]
Income Tax Disclosure [Line Items]
Net operating loss carryforwards	990,500,000
Deferred tax assets, valuation allowance	$ 2,800	$ 2,800