Accounts Receivable, Accounts Payable and Accrued Liabilities (Details 1) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Accounts Receivable, Net [Abstract]
Trade accounts receivable, less estimated returns, doubtful accounts and allowances	$ 538,532	$ 407,234
Other receivables	32,825	21,419
Accounts receivable, net	571,357	428,653
Returns, doubtful accounts and allowances	32,598	33,834	35,462
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Begining of Period		35,462	50,225
Additions - Charged to Costs and Expenses		57,245	70,693
Deductions		(58,873)	(85,456)
Balance at End of Period	32,598	33,834	35,462
Accounts payable and accrued liabilities	303,111	343,620
Accrued compensation and related benefits	161,231	162,079
Total accounts payable and accrued liabilities	464,342	505,699
Allowance for doubtful accounts and returns [Member]
Accounts Receivable, Net [Abstract]
Returns, doubtful accounts and allowances	32,598	33,834	33,612
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Begining of Period	33,834	33,612	48,199
Additions - Charged to Costs and Expenses	47,356	57,245	55,605
Deductions	(48,592)	(57,023)	(70,192)
Balance at End of Period	32,598	33,834	33,612
Allowance for advertising rate adjustments and discounts [Member]
Accounts Receivable, Net [Abstract]
Returns, doubtful accounts and allowances		0	1,850
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Begining of Period		1,850	2,026
Additions - Charged to Costs and Expenses		0	15,088
Deductions		(1,850)	(15,264)
Balance at End of Period		$ 0	$ 1,850