Schedule of Accounts Payable and Accrued Expenses (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Accounts Payable and Accrued Liabilities [Line Items]
Trade accounts payable	$ 53,230	$ 49,866
Accrued salaries and wages	39,411	29,766
Accrued dividends	51,156	51,496
Accrued workers' compensation and auto liability	6,737	6,652
Accrued litigation	7,822	9,290
Accrued employee medical insurance	6,506	8,413
Accrued property taxes	28,473	27,707
Accrued interest	11,949	9,526
Deferred revenue	13,633	14,332
Construction payable	3,903	7,845
Lease financing obligation	11,612	11,785
Other	43,372	33,429
Accounts payable and accrued expenses, total	$ 277,804	$ 260,107