CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands		Total	Hill Share of Stockholders' Equity	Common Stock	Additional Paid-in Capital	Retained Earnings (Deficit)	Accumulated Other Comprehensive (Loss)	Treasury Stock	Non-controlling Interests
Balance at beginning of period (in shares) at Dec. 31, 2018				62,181				6,546
Balance at beginning of period at Dec. 31, 2018		$ 94,445	$ 93,840	$ 6	$ 210,084	$ (85,444)	$ (2,575)	$ (28,231)	$ 605
Increase (decrease) in stockholders' equity
Net (loss) income		(368)	(518)			(518)			150
Other comprehensive income (loss)		(874)	(938)				(938)		64
Stock issued to Board of Directors (in shares)				24
Stock issued to Board of Directors		0
Share-based compensation expense		1,042	1,042		1,042
Stock issued under employee stock purchase plan (in shares)				57
Stock issued under employee stock purchase plan		113	113		113
Balance at end of period (in shares) at Jun. 30, 2019				62,262				6,546
Balance at end of period at Jun. 30, 2019		94,358	93,539	$ 6	211,239	(85,962)	(3,513)	$ (28,231)	819
Balance at beginning of period (in shares) at Dec. 31, 2018				62,181				6,546
Balance at beginning of period at Dec. 31, 2018		94,445	93,840	$ 6	210,084	(85,444)	(2,575)	$ (28,231)	605
Increase (decrease) in stockholders' equity
Net (loss) income		2,139
Balance at end of period (in shares) at Sep. 30, 2019				62,705				6,546
Balance at end of period at Sep. 30, 2019		97,882	97,031	$ 6	212,493	(83,481)	(3,756)	$ (28,231)	851
Balance at beginning of period (in shares) at Jun. 30, 2019				62,262				6,546
Balance at beginning of period at Jun. 30, 2019		94,358	93,539	$ 6	211,239	(85,962)	(3,513)	$ (28,231)	819
Increase (decrease) in stockholders' equity
Net (loss) income		2,507	2,481			2,481			26
Other comprehensive income (loss)		(237)	(243)				(243)		6
Stock issued to Board of Directors (in shares)				104
Stock issued to Board of Directors		$ 0
Share-based compensation expense (in shares)		322
Share-based compensation expense		$ 1,212	1,212		1,212
Stock issued under employee stock purchase plan (in shares)	[1]			17
Stock issued under employee stock purchase plan	[1]	42	42		42
Balance at end of period (in shares) at Sep. 30, 2019				62,705				6,546
Balance at end of period at Sep. 30, 2019		$ 97,882	97,031	$ 6	212,493	(83,481)	(3,756)	$ (28,231)	851
Balance at beginning of period (in shares) at Dec. 31, 2019		62,708		62,708				6,546
Balance at beginning of period at Dec. 31, 2019		$ 110,228	109,357	$ 6	212,759	(71,360)	(3,817)	$ (28,231)	871
Increase (decrease) in stockholders' equity
Net (loss) income		(8,358)	(8,535)			(8,535)			177
Other comprehensive income (loss)		4,746	5,096				5,096		(350)
Share-based compensation expense		1,201	1,201		1,201
Stock issued under employee stock purchase plan (in shares)				162
Stock issued under employee stock purchase plan		201	201		201
Transfer of shares pledged as collateral (in shares)	[2]			261				261
Transfer of shares pledged as collateral	[2]	(825)	(825)					$ (825)
Balance at end of period (in shares) at Jun. 30, 2020				62,609				6,807
Balance at end of period at Jun. 30, 2020		$ 107,193	106,495	$ 6	214,161	(79,895)	1,279	$ (29,056)	698
Balance at beginning of period (in shares) at Dec. 31, 2019		62,708		62,708				6,546
Balance at beginning of period at Dec. 31, 2019		$ 110,228	109,357	$ 6	212,759	(71,360)	(3,817)	$ (28,231)	871
Increase (decrease) in stockholders' equity
Net (loss) income		$ (6,113)
Balance at end of period (in shares) at Sep. 30, 2020		62,916		62,916				6,807
Balance at end of period at Sep. 30, 2020		$ 110,512	109,438	$ 6	214,596	(77,781)	1,673	$ (29,056)	1,074
Balance at beginning of period (in shares) at Jun. 30, 2020				62,609				6,807
Balance at beginning of period at Jun. 30, 2020		107,193	106,495	$ 6	214,161	(79,895)	1,279	$ (29,056)	698
Increase (decrease) in stockholders' equity
Net (loss) income		2,245	2,114			2,114			131
Other comprehensive income (loss)		639	394				394		245
Stock issued to Board of Directors (in shares)				291
Stock issued to Board of Directors		0
Share-based compensation expense		415	415		415
Stock issued under employee stock purchase plan (in shares)				16
Stock issued under employee stock purchase plan		$ 20	20		20
Balance at end of period (in shares) at Sep. 30, 2020		62,916		62,916				6,807
Balance at end of period at Sep. 30, 2020		$ 110,512	$ 109,438	$ 6	$ 214,596	$ (77,781)	$ 1,673	$ (29,056)	$ 1,074

[1] Included $21 of proceeds related to ESPP shares issued during the three months ended September 30, 2019 that were received in the subsequent period, but were excluded in Hill International, Inc.'s (the "Company") consolidated statements of cash flows.

[2] Reflects 261 shares of the Company's common stock pledged as collateral under the terms of a secured promissory note payable to the Company. During the three months ended March 31, 2020, the Company exercised its right to retain the shares upon the note holder's agreement to relinquish the shares upon the promissory note maturity date.