CORRECTION OF PRIOR PERIOD ERROR (Narrative) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Net earnings	$ 38,493	$ 11,299	$ 22,740	$ 41,312	$ 38,164	$ 34,493	$ 30,759	$ 22,973	$ 113,844	$ 126,389	$ 102,180
Retained earnings	1,261,377				1,163,925				1,261,377	1,163,925	1,052,000	965,000
Comprehensive Income Net Of Tax									123,467	64,071	118,972
ScenarioPreviouslyReportedMember
Net earnings					39,751		31,796	24,516		130,423	106,598
Retained earnings					1,187,989					1,187,989	1,071,000	981,000
Comprehensive Income Net Of Tax										68,000	124,000
RestatementAdjustmentMember
Net earnings					(1,587)		(1,037)	(1,543)		(4,034)	(4,418)
Retained earnings					(24,064)					(24,064)		16,000
Restatement Adjustment Noncumulative [Member]
Retained earnings					$ 23,000					$ 23,000