Income Taxes (Schedule of Components of Net Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
ASSETS
Accrued expenses	$ 21,065	$ 13,843
Accounts receivable reserves	2,363	2,624
Deferred revenue	7,637	10,618
Inventory basis differences	2,787	3,039
Property-based differences	1,652	1,324
Share-based compensation	9,267	9,035
Other	2,314	918
Net operating loss carryforwards	3,208	3,350
Tax credit carryforwards	10,226	8,096
Unrealized losses on foreign currency exchange contracts, interest rate swaps and investments	404	2,355
Total assets	60,923	55,202
Valuation allowance	(6,212)	(6,211)
Total assets, net of valuation allowance	54,711	48,991
Liabilities
Deferred instrument costs	(27,210)	(20,399)
Property-based differences	(32,494)	(31,859)
Intangible asset basis differences	(13,454)	(13,574)
Other	(432)	(656)
Unrealized gains on foreign currency exchange contracts, interest rate swaps and investments	(1,907)	(158)
Total liabilities	(75,497)	(66,646)
Net deferred tax assets (liabilities)	$ (20,786)	$ (17,655)