Income Taxes - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2017 USD ($) States	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Income Taxes Disclosure [Line Items]
Federal Statutory rate (percent)	35.00%	35.00%	35.00%
Provisional income tax benefit related to remeasurement of deferred tax balances	$ 49,200,000
Impact on state apportionment percentage changes on income tax expense (benefit)		$ (4,800,000)	$ 1,000,000
Operating loss carryforwards	$ 297,200,000
Operating loss carryforwards, expiration date start	2026
Operating loss carryforwards, expiration date end	2037
Net operating loss carryforwards, majority expiration date start	2024
Net operating loss carryforwards, majority expiration date end	2037
Number of states where net operating losses will likely be forfeited | States	6
Net deferred tax liabilities	$ 82,696,000	140,915,000
Foreign tax credits	19,453,000	21,492,000
Australian net operating loss carryforward	1,300,000
Valuation allowance - tax credit carryforwards	16,600,000
Valuation allowance - tax credit carryforwards recorded in 2014	7,500,000
Income taxes paid	1,231,000	2,637,000	$ 5,521,000
Unrecognized tax benefits	0
State and Local Jurisdiction [Member]
Income Taxes Disclosure [Line Items]
Operating loss carryforwards	$ 239,500,000
Operating loss carryforwards, expiration date end	2037
Valuation allowance - state NOL carryforwards	$ 5,998,000	$ 5,318,000
State and Local Jurisdiction [Member] | Valuation Allowance, Operating Loss Carryforwards [Member]
Income Taxes Disclosure [Line Items]
Valuation allowance - state NOL carryforwards	900,000
Australian Operation [Member]
Income Taxes Disclosure [Line Items]
Net deferred tax assets	3,300,000
Deferred tax assets, net operating loss	14,500,000
New Zealand Operation [Member]
Income Taxes Disclosure [Line Items]
Net deferred tax liabilities	$ 200,000