Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2017

Fair Value Disclosures [Abstract]

Summary of Placement in the Fair Value Hierarchy of Financial Assets that are Measured at Fair Value on a Recurring Basis

The following table presents the placement in the fair value hierarchy of financial assets that are measured at fair value on a recurring basis, including the items for which the fair value option has been elected, as of December 31, 2017:

	Quoted Prices in Active Markets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		December 31, 2017
Assets
U.S. government debt securities	$	—	$	5,998	$	—	$	5,998
Equity securities	10,537		4,563		—		15,100
Preferred stock	—		—		161,225		161,225
Other	—		850		—		850
Total	$	10,537	$	11,411	$	161,225	$	183,173

The following table presents the placement in the fair value hierarchy of financial assets that are measured at fair value on a recurring basis, including the items for which the fair value option has been elected, as of December 31, 2016:

	Quoted Prices in Active Markets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		December 31, 2016
Assets
U.S. government debt securities	$	—	$	180,323	$	—	$	180,323
Equity securities	15,544		7,978		—		23,522
Preferred stock	—		—		129,545		129,545
Other	—		1,917		—		1,917
Total	$	15,544	$	190,218	$	129,545	$	335,307

Schedule of Changes in Level 3 Liabilities

The changes in the fair value of the Level 3 liabilities during the years ended December 31, 2017 and 2016 were as follows:

	2017			2016
Beginning balance	$	2,081		$	—
Acquisition date fair value of contingent consideration liability	585			3,660
Payment of contingent consideration (Note 4)	—			(1,583		)
Change in fair value of contingent consideration recognized in selling, general and administrative expenses	(2,081		)	4
Ending balance	$	585		$	2,081