Accounts Receivable (Schedule of Accounts Receivable) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013	Dec. 31, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross trade accounts receivable	$ 365,435	$ 383,347
Deductions from trade accounts receivable	(271,139)	(240,061)	(197,991)	195,702
Allowance for doubtful accounts	(291)	(7)	0	0
Accounts receivable, net	94,005	143,279
Chargebacks [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Deductions from trade accounts receivable	(58,110)	(48,766)	(42,307)	41,670
Rebates and incentive programs [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Deductions from trade accounts receivable	(83,953)	(75,321)	(58,154)	59,426
Returns [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Deductions from trade accounts receivable	(84,590)	(78,181)	(71,084)	68,062
Cash discounts and other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Deductions from trade accounts receivable	$ (44,486)	$ (37,793)	$ (26,446)	$ 26,544