Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2017

Advertising costs for the years ended December 31, 2017, 2016 and 2015, are reflected in the following table (in thousands):



	Years Ended December 31,
	2017		2016		2015
Advertising Costs	$	49,433	$	47,312	$	44,015

Depreciation Expense Computed Using Straight-Line Method over Useful Lives

Depreciation expense is computed using the straight-line method over the following useful lives:



Computer hardware	2 to 3 years
Computer software	2 to 5 years
Furniture and equipment	5 years
Leasehold improvements	Term of lease, 5 years maximum

Property and equipment consisted of the following (in thousands):



	December 31,
	2017			2016
Computer hardware	$	171,515		$	170,746
Computer software	376,761			374,490
Furniture and equipment	102,424			100,472
Leasehold improvements	148,764			133,541
Other	9,907			9,993
Property and equipment, cost	809,371			789,242
Accumulated depreciation	(664,484		)	(627,733		)
Property and equipment, net	$	144,887		$	161,509

Internal-Use Software Development Costs Capitalized

Internal-use software development costs capitalized for the years ended December 31, 2017, 2016 and 2015, are reflected in the following table (in thousands):



	Years Ended December 31,
	2017		2016		2015
Internal-use software development costs	$	9,030	$	33,753	$	31,964