Subsequent Events - Additional Information (Detail) $ in Millions			6 Months Ended
	Jul. 20, 2018 USD ($)	Jul. 11, 2018 USD ($)	Jul. 01, 2018 Covenant	Jul. 19, 2018 USD ($)	Jul. 10, 2018 USD ($)
Term Loan Facility [Member]
Subsequent Event [Line Items]
Debt instrument, description			On July 11, 2018, the Company amended the Term Loan Facility to align certain of its terms with the Revolving Credit Facility, including (i) revisions to the calculation of the rates per annum at which borrowings under the Term Loan Facility bear interest, determined by reference to, at the Company’s option, either a base rate or a Eurodollar rate, to conform with the calculation of such rates under the Revolving Credit Facility, (ii) revisions to the calculation of the two financial covenants the Company is required to maintain, a “consolidated cash flow/fixed charges ratio” and a “consolidated funded indebtedness/cash flow ratio,” to conform with the calculation of such covenants under the Revolving Credit Facility and (iii) modifications to certain events of default to align with those under the Revolving Credit Facility, including the occurrence of unsatisfied judgments of the Company or its subsidiaries in excess of $100 million, as increased from $50 million, individually or in the aggregate, outstanding for 30 days or more which are not being appealed or contested in good faith.
Number of financial covenants | Covenant			2
Prudential Shelf Facility and NYL Shelf Facility [Member]
Subsequent Event [Line Items]
Debt instrument, description			On July 20, 2018, the Company amended each of the Prudential Shelf Facility and the NYL Shelf Facility primarily to align certain of their terms with the Revolving Credit Facility, specifically (i) revisions to the calculation of the two financial covenants the Company is required to maintain under each, a “consolidated cash flow/fixed charges ratio” and a “consolidated funded indebtedness/cash flow ratio,” to conform with the calculation of such covenants under the Revolving Credit Facility, (ii) modifications to certain events of default to align with those under the Revolving Credit Facility, including the occurrence of unsatisfied judgments of the Company or its subsidiaries in excess of $100 million, as increased from $50 million, individually or in the aggregate, outstanding for 30 days or more which are not being appealed or contested in good faith and (iii) revisions to certain negative covenants to reduce the existing limitations on the ability of the Company and its subsidiaries to dispose of assets outside of the ordinary course of business.
Number of financial covenants | Covenant			2
Subsequent Events [Member] | Term Loan Facility [Member]
Subsequent Event [Line Items]
Debt covenant modification to certain events of default excess amount | $		$ 100			$ 50
Debt covenant modification to certain events of default minimum period of outstanding		30 days
Subsequent Events [Member] | Prudential Shelf Facility and NYL Shelf Facility [Member]
Subsequent Event [Line Items]
Debt covenant modification to certain events of default excess amount | $	$ 100			$ 50
Debt covenant modification to certain events of default minimum period of outstanding	30 days