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Selected Quarterly Data Selected Quarterly Data - Additional Information (Details) (USD $)
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3 Months Ended | 9 Months Ended | 12 Months Ended | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
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Sep. 30, 2013
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Dec. 31, 2012
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Sep. 30, 2012
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Jun. 30, 2012
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Mar. 31, 2012
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Dec. 31, 2011
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Jun. 30, 2011
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Sep. 30, 2013
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Sep. 30, 2012
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Dec. 31, 2012
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Dec. 31, 2011
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Dec. 31, 2010
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| Quarterly Financial Information Disclosure [Abstract] | ||||||||||||
| Gain on lawsuit settlements | $ 700,000 | $ 500,000 | $ 8,400,000 | $ 8,300,000 | $ 17,200,000 | $ 17,900,000 | ||||||
| Change in fair value of contingent consideration liabilities | $ (712,000) | $ 200,000 | $ (1,892,000) | $ (1,200,000) | $ 1,300,000 | $ (200,000) | $ 1,600,000 | $ (1,765,000) | $ (1,787,000) | $ (1,643,000) | $ 1,408,000 | $ 0 |