Debt - Long-Term Debt (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Debt Instrument [Line Items]
Long-term debt, including current maturities	$ 301,046	$ 338,827
Less current maturities	2,115	17,868
Long-term debt, noncurrent	298,931	320,959
Parent Company [Member]
Debt Instrument [Line Items]
Long-term Debt, Total	298,520	299,120
Parent Company [Member] | 8% Unsecured Notes Due December 2019 [Member]
Debt Instrument [Line Items]
Long-term debt, total	173,578	173,578
Parent Company [Member] | 7.625% Unsecured Notes Due March 2027 [Member]
Debt Instrument [Line Items]
Long-term debt, total	116,880	116,880
Parent Company [Member] | Capitalized Leases and Other [Member]
Debt Instrument [Line Items]
Long-term debt, noncurrent	8,062	8,662
Subsidiaries [Member]
Debt Instrument [Line Items]
Long-term debt, total	2,526	39,707
Subsidiaries [Member] | 4.27% to 6.15% Unsecured Notes Due in 2014 [Member]
Debt Instrument [Line Items]
Long-term debt, total		15,560
Subsidiaries [Member] | 4.27% to 4.70% Unsecured Notes Due in 2015 [Member]
Debt Instrument [Line Items]
Long-term debt, total		8,554
Subsidiaries [Member] | 4.00% and 6.15% Unsecured Notes Due in 2016 [Member]
Debt Instrument [Line Items]
Long-term debt, total		11,036
Subsidiaries [Member] | 5.46% and 5.63% Secured Notes Due in 2016 [Member]
Debt Instrument [Line Items]
Long-term debt, total	$ 2,526	$ 4,557