Income Taxes (Schedule Of Deferred Income Tax Assets And Liabilities) (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Current
Assets:
Accruals not currently deductible	$ 2,605,711	$ 2,970,671
Stock based compensation	13,508,845	13,290,429
Impairment loss on available-for-sale securities	0	0
Intangible Assets	0	0
Other	4,440,407	4,713,241
Total deferred income tax assets	20,554,963	20,974,341
Liabilities:
Excess tax over book depreciation	0	0
Goodwill	0	0
Unrealized gain on investments	0	0
Intangible assets	0	0
Other	(1,117,956)	(558,249)
Net deferred income taxes	19,437,007	20,416,092
Non-Current
Assets:
Accruals not currently deductible	224,803	182,803
Stock based compensation	2,508,304	2,202,940
Impairment loss on available-for-sale securities	135,724	175,091
Intangible Assets	0	169,913
Other	19,765	40,203
Total deferred income tax assets	2,888,596	2,770,950
Liabilities:
Excess tax over book depreciation	(46,017,949)	(41,374,851)
Goodwill	(8,868,168)	(1,792,968)
Unrealized gain on investments	(6,368,670)	(10,482,468)
Intangible assets	(1,205,230)	0
Other
Net deferred income taxes	$ (59,571,421)	$ (50,879,337)