CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Allowance for doubtful accounts	$ 2,208,000	$ 2,636,000
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Common stock, shares issued (in shares)	53,850,427	53,774,221
Common stock, shares outstanding (in shares)	53,850,427	53,774,221
Convertible Notes Payable
Face amount of the Notes	$ 213,959,000	$ 160,090,000
Convertible debt
Stated interest rate	3.75%	3.75%
Senior Notes, due December 2019 \| Convertible Notes Payable
Stated interest rate	3.75%
Face amount of the Notes	$ 0	$ 15,702,000
Senior Notes, due December 2019 \| Convertible debt
Stated interest rate	4.75%	4.75%
Face amount of the Notes	$ 66,090,000	$ 75,090,000
Series B Senior Unsecured Convertible Notes \| Convertible Notes Payable
Face amount of the Notes	34,405,000	0
Term Loan \| Initial Term Loan
Face amount of the Notes	88,464,000	70,000,000
Convertible debt \| Series B Senior Unsecured Convertible Notes
Face amount of the Notes	34,405,000
Revolving Credit Facility \| Line of Credit
Face amount of the Notes	$ 25,000,000	$ 15,000,000

Amount of allowance for credit loss on accounts receivable, classified as current.

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