Note 9 — Accrued Expenses and Other Liabilities

The components of accrued expenses and other current liabilities were as follows:


	December 31,
	2018		2017
	(in thousands)
Payroll and related benefits	$	20,486	$	32,996
Warranty		7,852		6,532
Interest		4,321		4,430
Professional fees		2,897		3,942
Merger consideration payable		—		2,662
Sales, use, and other taxes		2,670		2,144
Restructuring liability		2,213		1,520
Other		6,011		3,842
Total	$	46,450	$	58,068

Customer deposits and deferred revenue

Customer deposits totaled $28.3 million and $41.5 million at December 31, 2018 and 2017, respectively, which are included in “Customer deposits and deferred revenue” in the Consolidated Balance Sheets. Deferred revenue represents amounts billed, other than deposits, in excess of the revenue that can be recognized on a particular contract at the balance sheet date. Changes in deferred revenue were as follows:


	(in thousands)
Balance - December 31, 2017	$	70,536
Deferral of revenue		10,251
Recognition of previously deferred revenue		(36,372)
Balance - December 31, 2018	$	44,415

As of December 31, 2018, the Company has approximately $74.0 million of remaining performance obligations on contracts with an original estimated duration of one year or more, of which approximately 67% is expected to be recognized within one year, with the remaining amounts expected to be recognized between one to three years. The Company has elected to exclude disclosures regarding remaining performance obligations that have an original expected duration of one year or less.

Other liabilities

As part of the acquisition of Ultratech, the Company assumed an executive non-qualified deferred compensation plan that allowed qualifying executives to defer cash compensation. The plan was frozen at the time of acquisition and no further contributions have been made. At December 31, 2018 and 2017, plan assets approximated $3.2 million and $3.4 million, respectively, representing the cash surrender value of life insurance policies and is included within “Other assets” in the Consolidated Balance Sheets, while plan liabilities approximated $3.5 million and $4.7 million, respectively and is included within “Other liabilities” in the Consolidated Balance Sheets. Other liabilities also included asset retirement obligations of $3.2 million and $3.3 million at December 31, 2018 and 2017, respectively, medical and dental benefits for former executives of $2.2 million at both December 31, 2018 and 2017, and income tax payables of $1.0 million at December 31, 2018.