Income Taxes (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Income Tax Disclosure [Abstract]
United States	$ 144,578	$ 111,376	$ 92,108
Foreign	(6,178)	5,727	2,518
Total	138,400	117,103	94,626
Current [Abstract]
Federal	43,871	32,850	29,040
State and other	5,958	7,675	5,682
Current tax	49,829	40,525	34,722
Deferred [Abstract]
Federal	6,071	4,754	1,715
State and other	844	40	656
Deferred tax	6,915	4,794	2,371
Total	56,744	45,319	37,093
Reconciliation of U.S. federal statutory tax rate to effective tax rate [Abstract]
Federal statutory rate (in hundredths)	35.00%	35.00%	35.00%
Change in valuation allowance (in hundredths)	1.97%	0.37%	0.81%
Other, primarily state income tax rate (in hundredths)	4.03%	3.33%	3.39%
Total effective tax rate (in hundredths)	41.00%	38.70%	39.20%
Deferred tax assets [Abstract]
Product inventories	7,703	8,075
Accrued expenses	2,780	2,885
Allowance for doubtful accounts	420	777
Total current	10,903	11,737
Less: Valuation Allowance, Current	(1,584)	(1,677)
Component reclassified for net presentation	(4,133)	(2,976)
Total current, net	5,186	7,084
Leases	1,957	1,866
Share-based compensation	16,970	17,740
Uncertain tax positions	1,226	1,650
Net operating losses	6,703	3,972
Interest rate swaps	1,327	164
Equity losses in unconsolidated investments	5,653	5,653
Other	1,150	1,037
Total noncurrent	34,986	32,082
Less: Valuation allowance, non-current	(10,772)	(7,948)
Component reclassified for net presentation	(23,474)	(23,461)
Total non-current, net	740	673
Total deferred tax assets	5,926	7,757
Deferred tax liabilities [Abstract]
Trade discounts on purchases	2,681	1,944
Prepaid expenses	1,452	1,032
Total current	4,133	2,976
Component reclassified for net presentation	(4,133)	(2,976)
Total current, net	0	0
Intangible assets, primarily goodwill	30,645	27,107
Depreciation	6,282	5,885
Total non-current	36,927	32,992
Component reclassified for net presentation	(23,474)	(23,461)
Total non-current, net	13,453	9,531
Total deferred tax liabilities	13,453	9,531
Net deferred tax liability	(7,527)	(1,774)
Operating Loss Carryforwards [Line Items]
Tax loss carry-forwards	23,923
Excess Tax Benefit (Tax Deficiency) from Share-based Compensation, Financing Activities	4,487	3,118	1,877
Uncertain tax positions activity [Roll Forward]
Beginning balance	4,715	3,962	4,550
Increases for tax positions taken during a prior period	0	0	114
Increases for tax positions taken during the current period	972	914	811
Decreases resulting from the expiration of the statute of limitations	(2,123)	(46)	(992)
Decreases relating to settlements	(60)	(115)	(521)
Ending balance	3,504	4,715	3,962
Unrecognized tax benefits that, if recognized, would decrease the effective tax rate	2,277	3,000
Interest (income) expense related to unrecognized tax benefits	(291)	307	70
Accrued interest on unrecognized tax benefits	511	802
International Subsidiaries [Member]
Operating Loss Carryforwards [Line Items]
Deferred tax asset, valuation allowance	(6,703)	(3,972)
Investment in Lac [Member]
Operating Loss Carryforwards [Line Items]
Deferred tax asset, valuation allowance	$ (5,653)