Condensed Consolidated Statements of Changes in Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Common stock	Additional paid-in capital	Treasury stock	Retained deficit	Retained deficit Cumulative Effect, Period of Adoption, Adjustment	Accumulated other comprehensive income / (loss)
Balance at beginning of period at Dec. 31, 2018	$ 1,030,126		$ 1,174	$ 1,214,928	$ (134,434)	$ 63,688		$ (115,230)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation expense	3,910			3,910
Restricted stock issuance, net of forfeitures	(925)		6	(931)
Shares issued in employee stock purchase plan	684		2	682
Contingent shares issued for acquisition of Cooper Valves	375		1	374
Treasury stock	(48)				(48)
Currency translation adjustment	4,834							4,834
Change in pension liability	(9)							(9)
Net loss	(7,888)					(7,888)
Balance at end of period at Mar. 31, 2019	1,031,059		1,183	1,218,963	(134,482)	55,800		(110,405)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adjustment for adoption of ASU 2016-13	486,039	$ (1,398)	1,189	1,231,650	(134,493)	(503,369)	$ (1,398)	(108,938)
Balance at beginning of period at Dec. 31, 2019	486,039	(1,398)	1,189	1,231,650	(134,493)	(503,369)	(1,398)	(108,938)
Balance at beginning of period at Dec. 31, 2019	486,039
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation expense	3,223			3,223
Restricted stock issuance, net of forfeitures	(173)		5	(178)
Shares issued in employee stock purchase plan	346		2	344
Adjustment for adoption of ASU 2016-13	442,062	$ (1,398)	1,196	1,235,039	(134,499)	(541,911)	$ (1,398)	(117,763)
Treasury stock	(6)				(6)
Currency translation adjustment	(8,846)							(8,846)
Change in pension liability	21							21
Net loss	(37,144)					(37,144)
Balance at end of period at Mar. 31, 2020	442,062		1,196	1,235,039	(134,499)	(541,911)		(117,763)
Balance at end of period at Mar. 31, 2020	442,062
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adjustment for adoption of ASU 2016-13	$ 442,062		$ 1,196	$ 1,235,039	$ (134,499)	$ (541,911)		$ (117,763)