Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2017

Fair Value Disclosures [Abstract]

Summary of Assets and Liabilities Measured at Fair Value on a Recurring Basis

The following table summarizes our assets and liabilities at December 31, 2017 and 2016 that are measured at fair value on a recurring basis subsequent to initial recognition and indicates the fair value hierarchy of the valuation techniques utilized by us to determine such fair value (in thousands):

	Level		December 31, 2017			December 31, 2016
Deferred compensation plan assets		1	$	85,589		$	69,912
Corporate and municipal bonds		1	$	51,101		$	44,573
Deferred compensation plan liabilities		1	$	(85,589	)	$	(69,912	)
Interest rate swap		2	$	1,131		$	529
Contingent purchase price liabilities		3	$	(37,574	)	$	(33,709	)

Change in Level 3 Fair Values of Contingent Purchase Price Liabilities

The following table summarizes the change in fair value of our contingent purchase price liabilities identified as Level 3 for the years ended December 31, 2017 and 2016 (pre-tax basis, in thousands):

	Contingent Purchase Price Liabilities
Beginning balance — January 1, 2016	$	(24,817	)
Additions from business acquisitions		(21,088	)
Settlement of contingent purchase price payable		11,202
Change in fair value of contingency		1,342
Change in net present value of contingency		(348	)
Balance — December 31, 2016	$	(33,709	)
Additions from business acquisitions		(19,291	)
Settlement of contingent purchase price payable		13,932
Change in fair value of contingency		2,128
Change in net present value of contingency		(634	)
Balance — December 31, 2017	$	(37,574	)