Quarterly Results (Unaudited) (Details) (USD $) In Thousands, except Per Share data	3 Months Ended								12 Months Ended
	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2009	Sep. 30, 2009	Jun. 30, 2009	Mar. 31, 2011	Mar. 31, 2010	Mar. 31, 2009
Notes to Financial Statements [Abstract]
Net sales	$ 379,985	$ 367,824	$ 382,271	$ 357,125	$ 278,020	$ 250,099	$ 226,661	$ 192,949	$ 1,487,205	$ 947,729	$ 903,297
Gross profit	225,591	216,397	225,005	207,443	168,471	145,996	123,340	96,435	874,436	534,242	516,504
Operating income	124,361	117,453	123,143	109,226	88,487	72,568	52,726	31,178	474,183	244,959	233,328
Net income from continuing operations	130,612	101,930	104,748	91,877					429,167	217,005	245,587
Net loss from discontinued operations	(5,084)	(1,154)	(1,668)	(2,311)					(10,217)	0	0
Net income									418,950	217,005	245,587
Diluted net income per common share - continuing operations	$ 0.65	$ 0.52	$ 0.55	$ 0.48					$ 2.20	$ 1.16	$ 1.31
Diluted net loss per common share - discontinued operations	$ (0.03)	$ (0.01)	$ (0.01)	$ (0.01)					$ (0.05)	$ 0.00	$ 0.00
Diluted net income per common share	$ 0.62	$ 0.51	$ 0.54	$ 0.47	$ 0.40	$ 0.37	$ 0.24	$ 0.15	$ 2.15	$ 1.16	$ 1.31
Quarterly financial data [Line Items]
Net sales	379,985	367,824	382,271	357,125	278,020	250,099	226,661	192,949	1,487,205	947,729	903,297
Gross profit	225,591	216,397	225,005	207,443	168,471	145,996	123,340	96,435	874,436	534,242	516,504
Operating income	124,361	117,453	123,143	109,226	88,487	72,568	52,726	31,178	474,183	244,959	233,328
Net income from continuing operations	130,612	101,930	104,748	91,877					429,167	217,005	245,587
Net loss from discontinued operations	(5,084)	(1,154)	(1,668)	(2,311)					(10,217)	0	0
Net income									418,950	217,005	245,587
Diluted net income per common share - continuing operations	$ 0.65	$ 0.52	$ 0.55	$ 0.48					$ 2.20	$ 1.16	$ 1.31
Diluted net loss per common share - discontinued operations	$ (0.03)	$ (0.01)	$ (0.01)	$ (0.01)					$ (0.05)	$ 0.00	$ 0.00
Diluted net income per common share	$ 0.62	$ 0.51	$ 0.54	$ 0.47	$ 0.40	$ 0.37	$ 0.24	$ 0.15	$ 2.15	$ 1.16	$ 1.31
First Quarter As Originally Reported [Member]
Notes to Financial Statements [Abstract]
Net sales				320,801
Gross profit				199,443
Operating income				106,632
Net income from continuing operations				89,615
Net loss from discontinued operations				(49)
Diluted net income per common share - continuing operations				$ 0.47
Diluted net income per common share				$ 0.47
Quarterly financial data [Line Items]
Net sales				320,801
Gross profit				199,443
Operating income				106,632
Net income from continuing operations				89,615
Net loss from discontinued operations				(49)
Diluted net income per common share - continuing operations				$ 0.47
Diluted net income per common share				$ 0.47
Adjustments [Member]
Notes to Financial Statements [Abstract]
Net sales				36,324
Gross profit				8,000
Operating income				2,594
Net income from continuing operations				2,262
Net loss from discontinued operations				(2,262)
Diluted net income per common share - continuing operations				$ 0.01
Diluted net loss per common share - discontinued operations				$ (0.01)
Quarterly financial data [Line Items]
Net sales				36,324
Gross profit				8,000
Operating income				2,594
Net income from continuing operations				2,262
Net loss from discontinued operations				(2,262)
Diluted net income per common share - continuing operations				$ 0.01
Diluted net loss per common share - discontinued operations				$ (0.01)
Adjusted First Quarter [Member]
Notes to Financial Statements [Abstract]
Net sales				357,125
Gross profit				207,443
Operating income				109,226
Net income from continuing operations				91,877
Net loss from discontinued operations				(2,311)
Diluted net income per common share - continuing operations				$ 0.48
Diluted net loss per common share - discontinued operations				$ (0.01)
Diluted net income per common share				$ 0.47
Quarterly financial data [Line Items]
Net sales				357,125
Gross profit				207,443
Operating income				109,226
Net income from continuing operations				91,877
Net loss from discontinued operations				$ (2,311)
Diluted net income per common share - continuing operations				$ 0.48
Diluted net loss per common share - discontinued operations				$ (0.01)
Diluted net income per common share				$ 0.47