Schedule of Accounts Payable and Accrued Expenses (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Accounts Payable and Accrued Liabilities [Line Items]
Trade accounts payable	$ 49,825	$ 49,826
Accrued salaries and wages	58,173	58,810
Accrued dividends	61,129	56,306
Accrued workers' compensation and auto liability	7,727	8,409
Accrued litigation	4,323	6,170
Accrued employee medical insurance	8,530	9,658
Accrued property taxes	24,522	24,721
Accrued interest	6,435	6,331
Deferred revenue	5,725	375
Construction payable	64,995	8,374
Other	26,182	23,297
Accounts payable and accrued expenses, total	$ 317,566	$ 252,277