During the second half of 2019, the Company implemented a restructuring plan to realign its expense structure with the reduction in revenue experienced in recent years and overall Company objectives. Management assessed the efficiency of our operations and consolidated locations and personnel, among other things, where possible. As part of this restructuring plan, the Company announced plans to reduce its overall operating expenses, both in the U.S and internationally.

In February 2019, the Company announced the restructuring of certain of our workforce predominantly in Germany, which included the closure of our office location in Munich, Germany accompanied by relocation or severance benefits for the affected employees. We also offered voluntary early retirement to certain other employees, which was announced in March 2019.

In January 2018, the Company announced an early retirement incentive program for employees that met certain defined requirements. The cumulative amount incurred during the year ended December 31, 2018 related to this restructuring program was $7.3 million. We did not incur any additional expenses related to this restructuring program during the year ended December 31, 2019.

A reconciliation of the beginning and ending restructuring liability, which is included in accrued wages and benefits in the Consolidated Balance Sheets as of December 31, 2019 and 2018, is as follows:

(In thousands)	2019			2018
Balance at beginning of period	$	185		$	205
Plus: Amounts charged to cost and expense		6,014			7,261
Less: Amounts paid		(4,631	)		(7,281	)
Balance at end of period	$	1,568		$	185

The components of restructuring expense in the Consolidated Statements of Income are for the years ended December 31, 2019, 2018 and 2017:

(In thousands)	2019		2018		2017
Selling, general and administrative expenses	$	2,360	$	2,655	$	152
Research and development expenses		2,869		1,831		122
Cost of sales		785		2,775		—
Total restructuring expenses	$	6,014	$	7,261	$	274

The following table represents the components of restructuring expense by geographic area for the years ended December 31, 2019, 2018 and 2017:

(In thousands)	2019		2018		2017
United States	$	3,336	$	7,120	$	274
International		2,678		141		—
Total restructuring expenses	$	6,014	$	7,261	$	274