Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Summary of Changes in Company's Allowance for Doubtful Accounts

Below is a summary of the changes in the Company’s allowance for doubtful accounts for the years ended December 31, 2018, 2017, and 2016.

	Balance at Beginning of Year		Provision		Acquired in Business Combinations		Write-offs, Net of Recoveries			Balance at End of Year
Year ended December 31, 2016	$	1,715	$	894		—	$	(648	)	$	1,961
Year ended December 31, 2017	$	1,961	$	806		—	$	(984	)	$	1,783
Year ended December 31, 2018	$	1,783	$	986		—	$	(670	)	$	2,099

Estimated Useful Lives of Property and Equipment and Other Capitalized Assets

Depreciation is calculated on the straight-line method based on the month the asset is placed in service over the following estimated useful lives:

	Estimated Useful Life
Furniture and fixtures	5 - 10 years
Computer equipment and software	3 years
Internal-use software and website development costs	3 - 5 years
Leasehold improvements	Shorter of useful life or remaining duration of lease

Property and Equipment and Other Capitalized Assets

Property and equipment and other capitalized assets consist of the following:

	As of December 31,
	2018			2017
Furniture and fixtures	$	1,266		$	1,554
Computer equipment and software		4,201			3,863
Leasehold improvements		3,844			2,887
Internal-use software and website development costs		29,692			26,702
		39,003			35,006
Less: accumulated depreciation and amortization		(28,102	)		(25,220	)
	$	10,901		$	9,786

Reconciliation of Numerator and Denominator Used in Calculation of Basic and Diluted Net Income Per Share

A reconciliation of the numerator and denominator used in the calculation of basic and diluted net income per share is as follows:

	For the Years Ended December 31,
	2018		2017		2016
Numerator:
Net income	$	12,955	$	6,803	$	2,419
Denominator:
Basic:
Weighted average shares of common stock and vested,    undelivered restricted stock units outstanding		27,738,178		27,550,044		29,953,798
Diluted:
Weighted average shares of common stock and vested,    undelivered restricted stock units outstanding		27,678,959		27,550,044		29,953,798
Effect of potentially dilutive shares		973,855		721,340		819,734
Total weighted average shares of common stock and vested,    undelivered restricted stock units outstanding and    potentially dilutive shares		28,652,814		28,271,384		30,773,532
Calculation of Net Income Per Common Share:
Basic:
Net income applicable to common stockholders	$	12,955	$	6,803	$	2,419
Weighted average shares of stock outstanding		27,738,178		27,550,044		29,953,798
Net income per common share	$	0.47	$	0.25	$	0.08
Diluted:
Net income applicable to common stockholders	$	12,955	$	6,803	$	2,419
Weighted average shares of stock outstanding		28,652,814		28,271,384		30,773,532
Net income per common share(1)	$	0.45	$	0.24	$	0.08

(1) In calculating diluted earnings per share, 0.5 million, 0.7 million, and 1.3 million shares related to outstanding stock options and unvested, undelivered restricted stock units were excluded for the years ended December 31, 2018, 2017, and 2016, respectively, because they were anti-dilutive.