FAIR VALUE OF FINANCIAL INSTRUMENTS (Debt) (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
5.51% Senior notes due 2017 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Interest rate	5.51%
3.84% Senior notes due 2021 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Interest rate	3.84%
3.70% Senior notes due 2023 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Interest rate	3.70%
3.85% Senior notes due 2025 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Interest rate	3.85%
4.24% Senior notes due 2026 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Interest rate	4.24%
4.05% Senior notes due 2028 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Interest rate	4.05%
4.11% Senior Notes [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Interest rate	4.11%
Reported Value Measurement [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Carrying Value	$ 972,035	$ 959,938
Reported Value Measurement [Member] | Industrial revenue bond, due 2023 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Carrying Value	8,400	8,400
Reported Value Measurement [Member] | Revolving credit agreement, due 2017 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Carrying Value	50,000	50,000
Reported Value Measurement [Member] | 5.51% Senior notes due 2017 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Carrying Value	150,000	150,000
Reported Value Measurement [Member] | 3.84% Senior notes due 2021 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Carrying Value	99,027	98,632
Reported Value Measurement [Member] | 3.70% Senior notes due 2023 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Carrying Value	225,000	225,000
Reported Value Measurement [Member] | 3.85% Senior notes due 2025 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Carrying Value	91,564	88,555
Reported Value Measurement [Member] | 4.24% Senior notes due 2026 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Carrying Value	180,096	173,557
Reported Value Measurement [Member] | 4.05% Senior notes due 2028 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Carrying Value	67,243	64,411
Reported Value Measurement [Member] | 4.11% Senior Notes [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Carrying Value	100,000	100,000
Reported Value Measurement [Member] | Other debt [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Carrying Value	705	1,383
Estimate of Fair Value Measurement [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Estimated Fair Value	969,875	946,389
Estimate of Fair Value Measurement [Member] | Industrial revenue bond, due 2023 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Estimated Fair Value	8,400	8,400
Estimate of Fair Value Measurement [Member] | Revolving credit agreement, due 2017 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Estimated Fair Value	50,000	50,000
Estimate of Fair Value Measurement [Member] | 5.51% Senior notes due 2017 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Estimated Fair Value	163,324	163,059
Estimate of Fair Value Measurement [Member] | 3.84% Senior notes due 2021 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Estimated Fair Value	99,027	98,632
Estimate of Fair Value Measurement [Member] | 3.70% Senior notes due 2023 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Estimated Fair Value	216,947	209,140
Estimate of Fair Value Measurement [Member] | 3.85% Senior notes due 2025 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Estimated Fair Value	91,564	88,555
Estimate of Fair Value Measurement [Member] | 4.24% Senior notes due 2026 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Estimated Fair Value	180,096	173,557
Estimate of Fair Value Measurement [Member] | 4.05% Senior notes due 2028 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Estimated Fair Value	67,243	64,411
Estimate of Fair Value Measurement [Member] | 4.11% Senior Notes [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Estimated Fair Value	92,569	89,252
Estimate of Fair Value Measurement [Member] | Other debt [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Estimated Fair Value	$ 705	$ 1,383