Condensed Consolidated Statements of Cash Flows (USD $)	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 153,048,925	$ 128,988,206
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	42,334,977	37,620,512
Loss on disposal of assets	2,114,241	327,382
Gain on sale of investments	(15,121,583)	(8,420,229)
Loss on sale of investments	805,805	841,274
Deferred income taxes	(6,271,382)	2,923,004
Stock-based compensation expense related to employee stock options, employee stock purchases and restricted stock	12,528,264	12,361,993
Excess tax benefits from stock-based compensation	(2,275,233)	(641,072)
Change in operating assets and liabilities:
Accounts receivable, net	(31,755,237)	(15,882,832)
Inventories	42,523,707	11,633,857
Prepaid expenses and other	(12,362)	4,403,912
Accounts payable	7,139,387	(13,236,250)
Accrued liabilities, excluding dividends declared	18,606,444	15,529,686
Net cash provided by operating activities	223,665,953	176,449,443
Activity in available-for-sale securities:
Sales proceeds	69,937,242	31,564,139
Maturities and calls	98,142,408	70,652,000
Purchases	(58,278,107)	(63,441,410)
Plant and equipment additions	(38,026,769)	(97,597,283)
Proceeds from sale of plant and equipment	316,449	1,012,608
Acquisition of businesses, net of cash acquired	(698,107,014)	0
(Increase) decrease in other assets	(602,017)	(16,036,911)
Net cash (used for) provided by investing activities	(626,617,808)	(73,846,857)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from borrowings on Credit Agreement	275,000,000	0
Financing costs paid	(953,800)	0
Issuance of common stock from stock plan transactions	22,526,742	8,417,982
Cash dividends paid	(58,898,029)	(54,829,734)
Repurchases of common stock	0	(33,716,725)
Excess tax benefits from stock-based compensation	2,275,233	641,072
Net cash provided by (used for) financing activities	239,950,146	(79,487,405)
NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS	(163,001,709)	23,115,181
CASH AND CASH EQUIVALENTS, beginning of period	389,678,664	357,986,774
CASH AND CASH EQUIVALENTS, end of period	$ 226,676,955	$ 381,101,955