Balance at

Charges

Beginning

(Reversals) to Cost

Balance at

of Year

or Expenses

Deductions

End of Year

Year Ended December 31, 2017:

Allowance for doubtful accounts

$

1,209

$

(401

)

$

(6

)

$

802

Allowance for sales returns

210

—

—

210

Allowance for tax valuation

54,310

(13,444

)

—

40,866

Year Ended December 31, 2016:

Allowance for doubtful accounts

$

1,765

$

(438

)

$

(118

)

$

1,209

Allowance for sales returns

210

—

—

210

Allowance for tax valuation

49,514

4,796

—

54,310

Year Ended December 31, 2015:

Allowance for doubtful accounts

$

1,711

$

86

$

(32

)

$

1,765

Allowance for sales returns

110

100

—

210

Allowance for tax valuation

42,069

7,445

—

49,514