Income Taxes (Schedule Of Components Of Net Deferred Tax Assets And Liabilities) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Current [Member]
Assets:
Accrued expenses	$ 19,833	$ 16,051
Accounts receivable reserves	1,153	828
Deferred revenue	5,872	3,915
Share-based compensation	2,325	2,337
Other	13	103
Net operating loss carryforwards	500	353
Unrealized losses on foreign currency exchange contracts, interest rate swaps and investments	1,580	1,688
Total assets	33,946	28,086
Valuation allowance	(642)	(579)
Total assets, net of valuation allowance	33,304	27,507
Liabilities:
Other	(190)	(96)
Unrealized gains on foreign currency exchange	(1,303)	(672)
Total liabilities	(1,493)	(768)
Net deferred tax assets (liabilities)	31,811	26,739
Long-Term [Member]
Assets:
Accrued expenses	1,622	1,542
Deferred revenue	1,552	781
Share-based compensation	7,923	8,084
Other	150	178
Net operating loss carryforwards	4,182	3,694
Total assets	17,157	15,743
Valuation allowance	(4,559)	(3,968)
Total assets, net of valuation allowance	12,598	11,775
Liabilities:
Deferred instrument costs	(3,093)	(2,263)
Property-based differences	(25,823)	(18,942)
Intangible assst basis differences	(15,513)	(12,614)
Other	(790)	(433)
Total liabilities	(45,219)	(34,252)
Net deferred tax assets (liabilities)	(32,621)	(22,477)
Inventory Based Differences [Member] | Current [Member]
Assets:
Inventory basis differences	2,670	2,811
Property-Based Differences [Member] | Long-Term [Member]
Assets:
Deferred tax asset	$ 1,728	$ 1,464