Income Taxes (Schedule Of Components Of Net Deferred Tax Assets And Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Current [Member]
Assets:
Accrued expenses	$ 23,298	$ 20,377
Accounts receivable reserves	2,973	2,591
Deferred revenue	7,392	8,697
Inventory basis differences	3,292	3,154
Share-based compensation	2,565	2,490
Other	234	171
Net operating loss carryforwards	65	65
Total assets	39,819	37,545
Valuation allowance	(507)	(457)
Total assets, net of valuation allowance	39,312	37,088
Liabilities:
Other	(550)	(610)
Unrealized gains on foreign currency exchange contracts, interest rate swaps and investments	(882)	(2,603)
Total liabilities	(1,432)	(3,213)
Net deferred tax assets	37,880	33,875
Long-Term [Member]
Assets:
Accrued expenses	5,329	7,824
Deferred revenue	3,656	3,084
Inventory basis differences	293	347
Property-based differences	1,524	1,601
Share-based compensation	10,580	8,936
Other	361	255
Net operating loss carryforwards	4,059	4,368
Unrealized losses on foreign currency exchange contracts, interest rate swaps and investments	53
Total assets	25,855	26,415
Valuation allowance	(3,939)	(4,221)
Total assets, net of valuation allowance	21,916	22,194
Liabilities:
Deferred instrument costs	(16,090)	(10,149)
Property-based differences	(35,079)	(33,978)
Intangible assst basis differences	(17,109)	(16,882)
Other	(1,460)	(517)
Total liabilities	(69,738)	(61,526)
Net deferred tax (liabilities)	$ (47,822)	$ (39,332)