Heidrick & Struggles International (HSII) 10-Q 29 Oct 18 2018 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2018	Oct. 29, 2018
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q3
Trading Symbol	HSII
Entity Registrant Name	HEIDRICK & STRUGGLES INTERNATIONAL INC
Entity Central Index Key	1,066,605
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		18,958,673

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($)	Sep. 30, 2018	Dec. 31, 2017
Current assets
Cash and cash equivalents	$ 164,216,000	$ 207,534,000
Accounts receivable, net	158,107,000	98,700,000
Prepaid expenses	25,083,000	22,003,000
Other current assets	29,783,000	11,620,000
Income taxes recoverable	5,763,000	3,933,000
Total current assets	382,952,000	343,790,000
Non-current assets
Property and equipment, net	35,491,000	39,514,000
Assets designated for retirement and pension plans	16,554,000	17,130,000
Investments	21,013,000	21,319,000
Other non-current assets	19,546,000	8,999,000
Goodwill	122,445,000	118,892,000
Other intangible assets, net	(2,535,000)	(2,158,000)
Deferred income taxes	32,320,000	35,402,000
Total non-current assets	249,904,000	243,414,000
Total assets	632,856,000	587,204,000
Current liabilities
Accounts payable	8,979,000	9,824,000
Accrued salaries and employee benefits	177,930,000	177,426,000
Deferred revenue	42,870,000	31,272,000
Other current liabilities	35,127,000	40,346,000
Income taxes payable	7,866,000	6,924,000
Total current liabilities	272,772,000	265,792,000
Long-term Line of Credit	0	0
Employee-related Liabilities, Non-current	40,946,000	40,308,000
Non-current liabilities
Retirement and pension plans	43,536,000	44,802,000
Other non-current liabilities	21,769,000	23,597,000
Total non-current liabilities	106,251,000	108,707,000
Total liabilities	379,023,000	374,499,000
Commitments and contingencies (Note 18)
Stockholders’ equity
Preferred stock, $0.01 par value, 10,000,000 shares authorized, no shares issued at June 30, 2018 and December 31, 2017	0	0
Common stock, $0.01 par value, 100,000,000 shares authorized, 19,585,777 shares issued, 18,954,271 and 18,781,433 shares outstanding at June 30, 2018 and December 31, 2017, respectively	196,000	196,000
Treasury stock at cost, 631,506 and 804,344 shares at June 30, 2018 and December 31, 2017, respectively	(20,298,000)	(26,096,000)
Additional paid in capital	224,962,000	226,006,000
Retained earnings (deficit)	44,854,000	(716,000)
Accumulated other comprehensive income	4,119,000	13,315,000
Total stockholders’ equity	253,833,000	212,705,000
Total liabilities and stockholders’ equity	$ 632,856,000	$ 587,204,000

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Preferred stock, par value (in USD per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Common stock, par value (in USD per share)	$ 0.01	$ 0.01
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	19,585,777	19,585,777
Common stock, shares outstanding	18,954,275	18,781,433
Treasury stock, shares	631,502	804,344

Condensed Consolidated Statemen

Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenue
Revenue before reimbursements (net revenue)	$ 187,588	$ 159,800	$ 530,718	$ 452,020
Reimbursements	4,753	4,665	13,970	13,740
Total revenue	192,341	164,465	544,688	465,760
Operating expenses
Salaries and employee benefits	133,933	108,546	373,021	309,159
General and administrative expenses	33,072	37,232	105,532	111,454
Goodwill and Intangible Asset Impairment	0	0	0	39,158
Reimbursed expenses	4,753	4,665	13,970	13,740
Total operating expenses	171,758	150,443	492,523	473,511
Operating income (loss)	20,583	14,022	52,165	(7,751)
Non-operating income (expense)
Interest, net	259	94	496	195
Other, net	2,345	147	1,849	(2,773)
Net non-operating expense	2,604	241	2,345	(2,578)
Income (loss) before income taxes	23,187	14,263	54,510	(10,329)
Provision for (benefit from) income taxes	(6,718)	(6,092)	(16,410)	902
Net income (loss)	16,469	8,171	38,100	(9,427)
Other comprehensive income (loss), net of tax
Foreign currency translation adjustment	(881)	995	(3,107)	5,779
Net unrealized gain on available-for-sale investments	0	624	0	1,858
Other comprehensive income (loss), net of tax	(881)	1,619	(3,107)	7,637
Comprehensive income (loss)	$ 15,588	$ 9,790	$ 34,993	$ (1,790)
Basic weighted average common shares outstanding (in shares)	18,954	18,781	18,905	18,720
Diluted weighted average common shares outstanding (in shares)	19,401	19,016	19,444	18,720
Basic net income per common share (in USD per share)	$ 0.87	$ 0.44	$ 2.02	$ (0.50)
Diluted net income per common share (in USD per share)	0.85	0.43	1.96	(0.50)
Cash dividends paid per share (in USD per share)	$ 0.13	$ 0.13	$ 0.39	$ 0.39

Condensed Consolidated Statem_2

Condensed Consolidated Statement of Changes in Stockholders' Equity (Unaudited) - 9 months ended Sep. 30, 2018 - USD ($) $ in Thousands	Total	Common Stock [Member]	Treasury Stock [Member]	Additional Paid in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income [Member]
Beginning balance at Dec. 31, 2017	$ 212,705	$ 196	$ (26,096)	$ 226,006	$ (716)	$ 13,315
Beginning balance, shares at Dec. 31, 2017	18,781,433	19,586,000	805,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	$ 38,100				38,100
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	8,954
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification | Accounting Standards Update 2014-09 [Member]					15,043
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification | Accounting Standards Update 2016-01 [Member]						(6,089)
Other comprehensive income, net of tax	(3,107)					(3,107)
Common and treasury stock transactions:
Stock-based compensation	6,763			6,763
Vesting of equity, net of tax withholdings	2,234		$ (5,604)	7,838
Vesting of equity, net of tax withholdings, shares			167,000
Re-issuance of treasury stock	(225)		$ (194)	(31)
Re-issuance of treasury stock, shares			6,000
Cash dividends declared ($0.26 per share)	(7,389)				(7,389)
Dividend equivalents on restricted stock units	184				184
Ending balance at Sep. 30, 2018	$ 253,833	$ 196	$ (20,298)	$ 224,962	$ 44,854	$ 4,119
Ending balance, shares at Sep. 30, 2018	18,954,275	19,586,000	632,000

Condensed Consolidated Statem_3

Condensed Consolidated Statement of Changes in Stockholders' Equity (Unaudited) (Parenthetical)	9 Months Ended
	Sep. 30, 2018$ / shares
Cash dividends per share	$ 0.39

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Condensed Cash Flow Statements, Captions [Line Items]
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	$ 164,814	$ 106,338
Cash flows - operating activities
Net income (loss)	38,100	(9,427)
Adjustments to reconcile net income (loss) to net cash used in operating activities:
Depreciation and amortization	9,558	11,270
Deferred income taxes	(438)	(15,340)
Stock-based compensation expense	6,763	3,915
Accretion expense related to earnout payments	(963)	(836)
Goodwill and Intangible Asset Impairment	0	39,158
Changes in assets and liabilities, net of effects of acquisitions:
Accounts receivable	60,057	32,603
Accounts payable	(761)	49
Accrued expenses	3,834	(38,043)
Restructuring Reserve, Accrual Adjustment	(10,833)	0
Deferred revenue	185	6,061
Income taxes payable, net	(2,003)	(44)
Retirement and pension plan assets and liabilities	(1,019)	2,798
Prepaid expenses	3,416	1,631
Other assets and liabilities, net	3,761	3,000
Net cash used in operating activities	(22,885)	(36,001)
Cash flows - investing activities
Payments to Acquire Businesses, Gross	(3,119)	(364)
Capital expenditures	(4,939)	(13,161)
Purchases of available-for-sale investments	(2,046)	(2,117)
Proceeds from sales of available-for-sale investments	2,890	1,271
Net cash used in investing activities	(7,214)	(14,371)
Proceeds from Lines of Credit	20,000	40,000
Repayments of Lines of Credit	(20,000)	(40,000)
Cash flows - financing activities
Cash dividends paid	(7,573)	(7,676)
Payment of employee tax withholdings on equity transactions	(2,234)	(2,392)
Payment for Contingent Consideration Liability, Financing Activities	0	4,557
Net cash used in financing activities	(9,807)	(14,625)
Effect of exchange rates fluctuations on cash, cash equivalents and restricted cash	(3,442)	5,766
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect	(43,348)	(59,231)
Cash, cash equivalents and restricted cash at end of period	$ 164,216	$ 105,718

Basis of Presentation of Interi

Basis of Presentation of Interim Financial Information	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Basis of Presentation of Interim Financial Information	Basis of Presentation of Interim Financial Information The accompanying unaudited Condensed Consolidated Financial Statements of Heidrick & Struggles International, Inc. and subsidiaries (the “Company”) have been prepared pursuant to the rules and regulations of the U.S. Securities and Exchange Commission (“SEC”). The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenue and expenses. Significant items subject to estimates and assumptions include revenue recognition, income taxes, interim effective tax rate and assessment of goodwill and other intangible assets for impairment. Estimates are subject to a degree of uncertainty and actual results could differ from these estimates. These financial statements and notes are to be read in conjunction with the Company’s Consolidated Financial Statements and Notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2017 , as filed with the SEC on March 13, 2018 .

Summary of Significant Accounti

Summary of Significant Accounting Policies (Notes)	9 Months Ended
	Sep. 30, 2018
Summary of Significant Accounting Policies [Abstract]
Significant Accounting Policies [Text Block]	Summary of Significant Accounting Policies A complete listing of the Company’s significant accounting policies is discussed in Note 2, Summary of Significant Accounting Policies , in the Notes to Consolidated Financial Statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2017 . Revenue Recognition As a result of the adoption of ASU 2014-09, Revenue from Contracts with Customers, the Company's accounting policy for revenue recognition has been updated. See Note 3 , Revenue. Restricted Cash The Company has lease agreements and business licenses with terms that require the Company to restrict cash through the termination dates of the agreements. Current and non-current restricted cash is included in Other current assets and Other non-current assets , respectively, in the Condensed Consolidated Balance Sheets. The following table provides a reconciliation of the cash and cash equivalents between the Condensed Consolidated Balance Sheets and the Condensed Consolidated Statement of Cash Flows as of September 30, 2018 and 2017 , and December 31, 2017 and 2016 : September 30, December 31, 2018 2017 2017 2016 Cash and cash equivalents $ 164,216 $ 105,718 $ 207,534 $ 165,011 Restricted cash included within other current assets 598 265 526 139 Restricted cash included within other non-current assets — 355 102 419 Total cash, cash equivalents and restricted cash $ 164,814 $ 106,338 $ 208,162 $ 165,569 Reclassifications Certain prior year amounts have been recast as a result of the change in the Company's operating segments and adoption of ASU No. 2016-18, Statement of Cash Flows: Restricted Cash. The reclassifications had no impact on net income, net cash flows or stockholders' equity. Earnings per Common Share Basic earnings per common share is computed by dividing net income by weighted average common shares outstanding for the period. Diluted earnings per share reflect the potential dilution that could occur if securities or other contracts to issue common stock were exercised or converted. Common equivalent shares are excluded from the determination of diluted earnings per share in periods in which they have an anti-dilutive effect. The following table sets forth the computation of basic and diluted earnings per share: Three Months Ended Nine Months Ended 2018 2017 2018 2017 Net income (loss) $ 16,469 $ 8,171 $ 38,100 $ (9,427 ) Weighted average shares outstanding: Basic 18,954 18,781 18,905 18,720 Effect of dilutive securities: Restricted stock units 278 187 345 — Performance stock units 169 48 194 — Diluted 19,401 19,016 19,444 18,720 Basic earnings per share $ 0.87 $ 0.44 $ 2.02 $ (0.50 ) Diluted earnings per share $ 0.85 $ 0.43 $ 1.96 $ (0.50 ) Weighted average restricted stock units and performance stock units outstanding that could be converted into approximately 327,000 and 80,000 common shares, respectively, for the nine months ended September 30, 2017, were not included in the computation of diluted earnings per share because the effects would be anti-dilutive. Recently Issued Financial Accounting Standards In February 2018, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") No. 2018-02, Income Statement - Reporting Comprehensive Income, intended to improve the usefulness of information reported as a result of the Tax Cuts and Jobs Act. The new guidance allows a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the Tax Cuts and Jobs Act. ASU 2018-02 is effective for interim and annual periods beginning after December 15, 2018, with early adoption permitted. The Company is currently evaluating the impact of this accounting guidance. The effect is not known or reasonably estimable at this time. In February 2016, the FASB issued ASU No. 2016-02, Leases, intended to improve financial reporting about leasing transactions. The new guidance will require entities that lease assets to recognize on their balance sheets the assets and liabilities for the rights and obligations created by those leases and to disclose key information about the leasing arrangements. ASU 2016-02 is effective for interim and annual periods beginning after December 15, 2018, with early adoption permitted. The guidance requires lessees and lessors to recognize and measure leases at the beginning of the earliest period presented using a modified retrospective approach. In July 2018, the FASB issued ASU No. 2018-11, Leases, intended to provide transition relief on comparative reporting at adoption. The ASU allows companies to present prior periods under current GAAP (Topic 840), rather than restating all periods presented under the new requirements of ASU No. 2016-02. ASU No. 2018-11 also eliminated the requirement that companies separate non-lease and lease components in a contract, and allows companies to account for those components as a single lease. The Company will adopt the guidance on January 1, 2019 using the modified retrospective method without restatement of the prior periods. As such, prior periods will continue to be presented under the existing ASC 840 lease accounting guidance. The Company is currently performing its evaluation of ASU 2016-02 and ASU 2018-11. The adoption of the guidance will have a material impact on the Company's Consolidated Balance Sheets with respect to recording a right-of-use asset and lease liability for each of the Company's leases. The Company's lease portfolio is primarily comprised of office leases, which are currently classified as operating leases and will continue to be classified as operating leases under the new guidance. The Company does not anticipate a significant change in expense recognition as it relates to the new guidance. Recently Adopted Financial Accounting Standards On January 1, 2018, the Company adopted ASU No. 2017-09, Compensation - Stock Compensation, Scope of Modification Accounting, which is intended to provide clarity and reduce both diversity in practice, cost and complexity when implementing a change in the terms or conditions of a share-based payment award. ASU 2017-09 requires that an entity should account for the effects of a modification unless the fair value, vesting conditions and whether the award is classified as a liability instrument or an equity instrument remain unchanged in the modification. The adoption of this guidance did not have an impact on the Company's financial statements. The future impact of this accounting guidance will be dependent on future modification events including the number of awards modified. On January 1, 2018, the Company adopted ASU No. 2017-07, Compensation - Retirement Benefits: Improving the Presentation of Net Periodic Pension Cost and Net Periodic Post-retirement Benefit Cost, which is intended to improve the consistency, transparency and usefulness of net benefit cost disclosures. ASU 2017-07 requires that an employer report the service cost component of net benefit cost in the same line item or items as other compensation costs arising from services rendered by the pertinent employees during the period. Additionally, the other components of net benefit costs are required to be presented in the income statement separately from the service cost component and outside a subtotal of income from operations. The adoption of this guidance did not have an impact on the Company's financial statements. On January 1, 2018, the Company adopted ASU No. 2016-18, Statement of Cash Flows: Restricted Cash, which requires that the statement of cash flows explain the change during the period in the total of cash, cash equivalents and amounts generally described as restricted cash or restricted cash equivalents. Therefore, amounts generally described as restricted cash should be included with cash and cash equivalents when reconciling the beginning of period and end of period total amounts shown on the statement of cash flows. The adoption of this guidance increased the Company's beginning and ending balances of cash, cash equivalents and restricted cash in the Condensed Consolidated Statement of Cash Flows by approximately $0.6 million for each period presented. Changes in the Company's restricted cash balances between periods are immaterial. On January 1, 2018, the Company adopted ASU No. 2016-15, Statement of Cash Flows: Classification of Certain Cash Receipts and Cash Payments, which is intended to reduce diversity in practice as to how certain cash receipts and cash payments should be presented and classified. The adoption of this guidance did not have an impact on the Company's financial statements. On January 1, 2018, the Company adopted ASU 2016-01, Financial Instruments: Recognition and Measurement of Financial Assets and Financial Liabilities, which addresses certain aspects of recognition, measurement, presentation and disclosure of financial instruments including the recognition of unrealized changes in fair value within net income. The adoption of this guidance resulted in a reclassification of accumulated unrealized gains of approximately $6.1 million from accumulated other comprehensive income to retained earnings. The impact of the adoption of this guidance on the Company's Condensed Consolidated Statement of Comprehensive Income for the nine months ended September 30, 2018, was not material. The comparative periods have not been restated and continue to be reported under the accounting standards in effect for those periods. On January 1, 2018, the Company adopted ASU No. 2014-09, Revenue from Contracts with Customers, using the modified retrospective method. The Company applied the guidance to all contracts that were not complete as of the adoption date. The guidance requires that an entity recognizes revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the Company expects to be entitled in exchange for these goods or services. The Company recognized the cumulative effect of initially applying the new guidance as an adjustment to the opening balance of retained earnings. The comparative periods have not been restated and continue to be reported under the accounting standards in effect for those periods. Impacts on Financial Statements of Recently Adopted Financial Accounting Standards The cumulative effect of the changes made to our Condensed Consolidated Balance Sheet as of January 1, 2018 as a result of the adoption of ASU 2014-09, Revenue from Contracts with Customers, and ASU 2016-01, Financial Instruments: Recognition and Measurement of Financial Assets and Financial Liabilities was as follows: December 31, ASU 2014-09 Adjustments ASU 2016-01 Adjustments January 1, Current assets Other current assets $ 11,620 $ 14,689 $ — $ 26,309 Total current assets 343,790 14,689 — 358,479 Non-current assets Deferred income taxes 35,402 (3,099 ) — 32,303 Total non-current assets 243,414 (3,099 ) — 240,315 Total assets $ 587,204 $ 11,590 $ — $ 598,794 Current liabilities Deferred revenue 31,272 (1,059 ) — 30,213 Other current liabilities 40,346 3,695 — 44,041 Total current liabilities 265,792 2,636 — 268,428 Total liabilities $ 374,499 $ 2,636 $ — $ 377,135 Stockholders' equity Retained earnings (deficit) (716 ) 8,954 6,089 14,327 Accumulated other comprehensive income 13,315 — (6,089 ) 7,226 Total stockholders’ equity 212,705 8,954 — 221,659 Total liabilities and stockholders’ equity $ 587,204 $ 11,590 $ — $ 598,794 The impact of ASU 2014-09, Revenue from Contracts with Customers, on our Condensed Consolidated Balance Sheet as of September 30, 2018 was as follows: September 30, 2018 As Reported Balances Without Adoption of ASU 2014-09 Effect of Adoption Higher/(Lower) Current assets Other current assets $ 29,783 $ 12,678 $ 17,105 Total current assets 382,952 365,847 17,105 Non-current assets Deferred income taxes 32,320 35,419 (3,099 ) Total non-current assets 249,904 253,003 (3,099 ) Total assets $ 632,856 $ 618,850 $ 14,006 Current liabilities Accrued salaries and employee benefits 177,930 176,984 946 Deferred revenue 42,870 43,531 (661 ) Other current liabilities 35,127 30,760 4,367 Income taxes payable 7,866 7,746 120 Total current liabilities 272,772 268,000 4,772 Total liabilities $ 379,023 $ 374,251 $ 4,772 Stockholders' equity Retained earnings (deficit) 44,854 35,620 9,234 Total stockholders’ equity 253,833 244,599 9,234 Total liabilities and stockholders’ equity $ 632,856 $ 618,850 $ 14,006 The impact of ASU 2014-09, Revenue from Contracts with Customers, on our Condensed Consolidated Statement of Comprehensive Income for the three and nine months ended September 30, 2018 was as follows: Three Months Ended September 30, 2018 Nine Months Ended September 30, 2018 As Reported Balances Without Adoption of ASU 2014-09 Effect of Adoption Higher/(Lower) As Reported Balances Without Adoption of ASU 2014-09 Effect of Adoption Higher/(Lower) Revenue Revenue before reimbursements (net revenue) $ 187,588 $ 187,720 $ (132 ) $ 530,718 $ 529,372 $ 1,346 Reimbursements 4,753 4,753 — 13,970 13,970 — Total revenue 192,341 192,473 (132 ) 544,688 543,342 1,346 Operating expenses Salaries and employee benefits 133,933 134,017 (84 ) 373,021 372,075 946 General and administrative expenses 33,072 33,072 — 105,532 105,532 — Reimbursed expenses 4,753 4,753 — 13,970 13,970 — Total operating expenses 171,758 171,842 (84 ) 492,523 491,577 946 Operating income 20,583 20,631 (48 ) 52,165 51,765 400 Non-operating income (expense) Interest, net 259 259 — 496 496 — Other, net 2,345 2,345 — 1,849 1,849 — Net non-operating income (expense) 2,604 2,604 — 2,345 2,345 — Income before income taxes 23,187 23,235 (48 ) 54,510 54,110 400 Provision for income taxes 6,718 6,736 (18 ) 16,410 16,290 120 Net income $ 16,469 $ 16,499 $ (30 ) $ 38,100 $ 37,820 $ 280 Basic earnings per share $ 0.87 $ 0.87 $ — $ 2.02 $ 2.00 $ 0.02 Diluted earnings per share $ 0.85 $ 0.85 $ — $ 1.96 $ 1.95 $ 0.01 The impact of ASU 2014-09, Revenue from Contracts with Customers, on our Condensed Consolidated Statement of Cash Flows for the nine months ended September 30, 2018 was as follows: Nine Months Ended September 30, 2018 As Reported Balances Without Adoption of ASU 2014-09 Effect of Adoption Higher/(Lower) Cash flows - operating activities Net income $ 38,100 $ 37,820 $ 280 Changes in assets and liabilities, net of effects of acquisitions: Accrued expenses 3,834 (1,479 ) 5,313 Deferred revenue 185 2,843 (2,658 ) Income taxes payable, net (2,003 ) (2,123 ) 120 Other assets and liabilities, net $ (3,761 ) $ (705 ) $ (3,056 )

Revenue (Notes)

Revenue (Notes)	9 Months Ended
	Sep. 30, 2018
Unbilled Receivables, Contract Assets and Liabilities [Line Items]
Revenue Recognition, Multiple-deliverable Arrangements, Description [Policy Text Block]	Revenue Executive Search Revenue is recognized as we satisfy our performance obligations by transferring a good or service to a client. Generally, each of our executive search contracts contain one performance obligation which is the process of identifying potentially qualified candidates for a specific client position. In most contracts, the transaction price includes both fixed and variable consideration. Fixed compensation is comprised of a retainer, equal to approximately one-third of the estimated first year compensation for the position to be filled, and indirect expenses, equal to a specified percentage of the retainer, as defined in the contract. The Company generally bills its clients for its retainer and indirect expenses in one-third increments over a three-month period commencing in the month of a client’s acceptance of the contract. If actual compensation of a placed candidate exceeds the original compensation estimate, the Company is often authorized to bill the client for one-third of the excess compensation. The Company refers to this additional billing as uptick revenue. In most contracts, variable consideration is comprised of uptick revenue and direct expenses. The Company bills its clients for uptick revenue upon completion of the executive search, and direct expenses are billed as incurred. As required under ASU 2014-09, and as described in Note 2, Summary of Significant Accounting Policies , the Company now estimates uptick revenue at contract inception, based on a portfolio approach, utilizing the expected value method based on a historical analysis of uptick revenue realized in the Company’s geographic regions and industry practices, and initially records a contract’s uptick revenue in an amount that is probable not to result in a significant reversal of cumulative revenue recognized when the actual amount of uptick revenue for that contract is known. Differences between the estimated and actual amounts of variable consideration are recorded when known. The Company does not estimate revenue for direct expenses as it is not materially different than recognizing revenue as direct expenses are incurred. Revenue from our executive search engagement performance obligation is recognized over time as our clients simultaneously receive and consume the benefits provided by the Company's performance. Revenue from executive search engagements is recognized over the expected average period of performance, in proportion to the estimated personnel time incurred to fulfill our obligations under the executive search contract. Revenue is generally recognized over a period of approximately six months. Our executive search contracts contain a replacement guarantee which provides for an additional search to be completed, free of charge except for expense reimbursements, should the candidate presented by the Company be hired by the client and subsequently terminated by the client for performance reasons within a specified period of time. The replacement guarantee is an assurance warranty, which is not a performance obligation under the terms of the executive search contract, as the Company does not provide any services under the terms of the guarantee that transfer benefits to the client in excess of assuring that the identified candidate complies with the agreed-upon specifications. The Company accounts for the replacement guarantee under the relevant warranty guidance in ASC 460 - Guarantees. Heidrick Consulting Revenue is recognized as we satisfy our performance obligations by transferring a good or service to a client. Heidrick Consulting enters into contracts with clients that outline the general terms and conditions of the assignment to provide succession planning, executive assessment, top team and board effectiveness and culture shaping programs. The consideration the Company expects to receive under each contract is generally fixed. Most of our consulting contracts contain one performance obligation, which is the overall process of providing the consulting service requested by the client. The majority of our consulting revenue is recognized over time utilizing both input and output methods. Contracts that contain coaching sessions, training sessions or the completion of assessments are recognized using the output method as each session or assessment is delivered to the client. Contracts that contain general consulting work are recognized using the input method utilizing a measure of progress that is based on time incurred on the project. The Company enters into enterprise agreements with clients to provide a license for online access, via the Company's SD Connect platform, to training and other proprietary material related to the Company's culture shaping programs. The consideration the Company expects to receive under the terms of an enterprise agreement is comprised of a single fixed fee. Our enterprise agreements contain multiple performance obligations, the delivery of materials via SD Connect and material rights related to options to renew enterprise agreements at a significant discount. The Company allocates the transaction price to the performance obligations in the contract on a stand-alone selling price basis. The stand-alone selling price for the initial term of the enterprise agreement is outlined in the contract and is equal to the price paid by the client for the agreement over the initial term of the contract. The stand-alone selling price for the options to renew, or material right, are not directly observable and must be estimated. This estimate is required to reflect the discount the client would obtain when exercising the option to renew, adjusted for the likelihood that the option will be exercised. The Company estimates the likelihood of renewal using a historical analysis of client renewals. Access to SD Connect represents a right to access the Company’s intellectual property that the client simultaneously receives and consumes as the Company performs under the agreement, and therefore the Company recognizes revenue over time. Given the continuous nature of this commitment, the Company utilizes straight-line ratable revenue recognition over the estimated subscription period as the Company's clients will receive and consume the benefits from SD Connect equally throughout the contract period. Revenue related to client renewals of enterprise agreements is recognized over the term of the renewal, which is generally twelve months. Enterprise agreements do not comprise a significant portion of the Company's revenue. Contract Balances Contract assets and liabilities are reported in a net position on a contract-by-contract basis at the end of each reporting period. Contract assets and liabilities are classified as current due to the nature of the Company's contracts, which are completed within one year. Contract assets are included within Other Current Assets on the Condensed Consolidated Balance Sheets. Unbilled receivables: Unbilled revenue represents contract assets from revenue recognized over time in excess of the amount billed to the client and the amount billed to the client is solely dependent upon the passage of time. This amount includes revenue recognized in excess of billed executive search retainers and Heidrick Consulting fees. Contract assets: Contract assets represent revenue recognized over time in excess of the amount billed to the client and the amount billed to the client is not solely subject to the passage of time. This amount primarily includes revenue recognized for upticks and contingent placement fees in executive search contracts. Deferred revenue: Contract liabilities consist of deferred revenue, which is equal to billings in excess of revenue recognized. The following table outlines the changes in our contract asset and liability balances during the period: January 1, September 30, Variance Contract assets Unbilled receivables $ 5,487 $ 7,655 $ 2,168 Contract assets 12,398 14,334 1,936 Contract liabilities Deferred revenue $ 30,370 $ 42,870 $ 12,500 During the nine months ended September 30, 2018, we recognized revenue of $27.4 million that was included in the contract liabilities balance at the beginning of the period. The amount of revenue recognized during the nine months ended September 30, 2018, from performance obligations partially satisfied in previous periods as a result of changes in the estimates of variable consideration was $20.9 million . Each of the Company's contracts has an expected duration of one year or less. Accordingly, the Company has elected to utilize the available practical expedient related to the disclosure of the transaction price allocated to the remaining performance obligations under its contracts. The Company has also elected the available practical expedients related to adjusting for the effects of a significant financing component and the capitalization of contract acquisition costs. The Company charges and collects from its clients, sales tax and value added taxes as required by certain jurisdictions. The Company has made an accounting policy election to exclude these items from the transaction price in its contracts.

Allowance for Doubtful Accounts

Allowance for Doubtful Accounts	9 Months Ended
	Sep. 30, 2018
Receivables [Abstract]
Allowance for Doubtful Accounts	Allowance for Doubtful Accounts The activity of the allowance for doubtful accounts is as follows: Balance at December 31, 2017 $ 2,534 Provision charged to income 3,899 Write-offs, net of recoveries (1,203 ) Foreign currency translation (99 ) Balance at September 30, 2018 $ 5,131

Property and Equipment, net

Property and Equipment, net	9 Months Ended
	Sep. 30, 2018
Property, Plant and Equipment [Abstract]
Property and Equipment, net	Property and Equipment, net The components of the Company’s property and equipment are as follows: September 30, December 31, Leasehold improvements $ 47,863 $ 48,216 Office furniture, fixtures and equipment 17,960 17,732 Computer equipment and software 27,427 28,300 Property and equipment, gross 93,250 94,248 Accumulated depreciation (57,759 ) (54,734 ) Property and equipment, net $ 35,491 $ 39,514 Depreciation expense for the three months ended September 30, 2018 and 2017 was $2.7 million and $2.8 million , respectively. Depreciation expense for the nine months ended September 30, 2018 and 2017 was $8.3 million and $7.4 million , respectively.

Investments

Investments	9 Months Ended
	Sep. 30, 2018
Investments Schedule [Abstract]
Investments	Investments The Company has a U.S. non-qualified deferred compensation plan that consists primarily of U.S. marketable securities and mutual funds, all of which are valued using Level 1 inputs (See Note 7 , Fair Value Measurements ). The fair value for these investments was $21.0 million and $21.3 million as of September 30, 2018 and December 31, 2017 , respectively. The aggregate cost basis for these investments was $14.8 million and $14.6 million as of September 30, 2018 and December 31, 2017 , respectively.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. A three-level fair value hierarchy prioritizes the inputs used to measure fair value. The hierarchy requires entities to maximize the use of observable inputs and minimize the use of unobservable inputs. The three levels of inputs used to measure fair value are as follows: • Level 1 – Quoted prices in active markets for identical assets and liabilities. • Level 2 – Quoted prices in active markets for similar assets and liabilities, or other inputs that are observable for the asset or liability, either directly or indirectly, for substantially the full term of the financial instrument. • Level 3 – Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets and liabilities. This includes certain pricing models, discounted cash flow methodologies and similar techniques that use significant unobservable inputs. The following tables provide a summary of the fair value measurements at September 30, 2018 , and December 31, 2017 , for each major category of assets and liabilities measured at fair value on a recurring basis: Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Balance at September 30, 2018 U.S. non-qualified deferred compensation plan $ 21,013 $ — $ — $ 21,013 Assets designated for retirement and pension plans — 17,965 — 17,965 Pension benefit obligation — (23,089 ) — (23,089 ) Acquisition earnout accruals — — (10,490 ) (10,490 ) $ 21,013 $ (5,124 ) $ (10,490 ) $ 5,399 Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Balance at December 31, 2017 U.S. non-qualified deferred compensation plan $ 21,319 $ — $ — $ 21,319 Assets designated for retirement and pension plans — 18,590 — 18,590 Pension benefit obligation — (23,886 ) — (23,886 ) Acquisition earnout accruals — — (7,213 ) (7,213 ) $ 21,319 $ (5,296 ) $ (7,213 ) $ 8,810 The Level 2 assets above are reinsurance contracts fair valued in accordance with BaFin - German Federal Financial Supervisory Authority guidelines, which utilize observable inputs including mortality tables and discount rates. The Level 3 liabilities include accruals for future earnout payments related to prior acquisitions, the values of which are determined based on discounted cash flow models. The Company considers the recorded value of its financial assets and liabilities, which consist primarily of cash and cash equivalents, accounts receivable, and accounts payable, to approximate the fair value of the respective assets and liabilities at September 30, 2018 , and December 31, 2017 , based upon the short-term nature of the assets and liabilities. The following table provides a reconciliation of the beginning and ending balance of Level 3 assets and liabilities for the nine months ended September 30, 2018 : Acquisition Balance at December 31, 2017 $ (7,213 ) Acquisition earnouts (Note 8) (3,054 ) Earnout accretion (963 ) Philosophy IB earnout adjustment (1) 436 Foreign currency translation 304 Balance at September 30, 2018 $ (10,490 ) (1) During the three months ended September 30, 2018 , the Company determined that the software and consulting revenue targets for the period from September 2017 to August 2018, or second installment, would not be achieved. As such, the Company reduced the second installment earnout accrual by $0.4 million .

Acquisitions

Acquisitions	9 Months Ended
	Sep. 30, 2018
Business Combinations [Abstract]
Acquisitions	Acquisitions On January 4, 2018 , the Company acquired Amrop A/S ("Amrop"), a Denmark-based provider of executive search services for 24.3 million Danish Kroner (equivalent to $3.9 million on the acquisition date) of initial consideration which was funded from existing cash. The former owners of Amrop are expected to receive additional cash consideration based on fee revenue generated during the two-year period following the completion of the acquisition. When estimating the value of future cash consideration, the Company accrued $3.1 million on the acquisition date. The Company recorded $1.7 million of intangible assets related to customer relationships and $5.1 million of goodwill. The goodwill is primarily related to the acquired workforce and strategic fit.

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	9 Months Ended
	Sep. 30, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Other Intangible Assets	Goodwill and Other Intangible Assets Goodwill The Company's goodwill by segment is as follows: September 30, December 31, 2017 Executive Search Americas $ 88,595 $ 88,690 Europe 48,601 44,407 Asia Pacific 8,756 9,302 Total Executive Search 145,952 142,399 Heidrick Consulting 36,257 36,257 Goodwill, gross 182,209 178,656 Accumulated impairment (59,764 ) (59,764 ) Goodwill, net $ 122,445 $ 118,892 Changes in the carrying amount of goodwill by segment for the nine months ended September 30, 2018 , are as follows: Executive Search Heidrick Consulting Americas Europe Asia Pacific Total Gross goodwill at December 31, 2017 $ 88,690 $ 44,407 $ 9,302 $ 36,257 $ 178,656 Accumulated impairment — (23,507 ) — (36,257 ) (59,764 ) Net goodwill at December 31, 2017 88,690 20,900 9,302 — 118,892 Amrop acquisition — 5,102 — — 5,102 Foreign currency translation (95 ) (908 ) (546 ) — (1,549 ) Net goodwill at September 30, 2018 $ 88,595 $ 25,094 $ 8,756 $ — $ 122,445 On January 4, 2018, the Company acquired Amrop and included the fair value of the acquired assets and liabilities as of the acquisition date in the Condensed Consolidated Balance Sheets. The Company included $5.1 million of goodwill related to the acquisition in the Europe segment. During the nine months ended September 30, 2017, the Company determined that the goodwill within the Culture Shaping reporting unit was impaired, which resulted in an impairment charge of $29.3 million to write off all goodwill in the Culture Shaping reporting unit. The impairment charge is recorded within Impairment charges in the Condensed Consolidated Statements of Comprehensive Income (Loss) for the nine months ended September 30, 2017. The impairment was non-cash in nature and did not affect our current liquidity, cash flows, borrowing capability or operations, nor did it impact the debt covenants under our credit agreement. Effective January 1, 2018, the Company completed its integration of the Culture Shaping reporting unit into the newly created Heidrick Consulting reporting unit. Other Intangible Assets, net The Company’s other intangible assets, net by segment, are as follows: September 30, December 31, 2017 Executive Search Americas $ 73 $ 252 Europe 2,378 1,799 Asia Pacific 84 107 Total Executive Search 2,535 2,158 Heidrick Consulting — — Total other intangible assets, net $ 2,535 $ 2,158 The Company recorded customer relationships in the Europe segment of $1.7 million related to the acquisition of Amrop. During the nine months ended September 30, 2017, the Company determined that the intangible assets within the Culture Shaping reporting unit were impaired, which resulted in an impairment charge of $9.9 million to write off all intangible assets in the Culture Shaping reporting unit. The impairment charge is recorded within Impairment charges in the Condensed Consolidated Statements of Comprehensive Income (Loss) for the nine months ended September 30, 2017. The impairment was non-cash in nature and did not affect current liquidity, cash flows, borrowing capability or operations, nor did it impact the debt covenants under our credit agreement. The carrying amount of amortizable intangible assets and the related accumulated amortization are as follows: Weighted September 30, 2018 December 31, 2017 Gross Carrying Amount Accumulated Amortization Net Carrying Amount Gross Carrying Amount Accumulated Amortization Net Carrying Amount Client relationships 6.8 $ 16,053 $ (13,518 ) $ 2,535 $ 13,703 $ (11,612 ) $ 2,091 Trade name 0.0 443 (443 ) — 459 (459 ) — Non-compete 0.0 222 (222 ) — 230 (163 ) 67 Total intangible assets 6.8 $ 16,718 $ (14,183 ) $ 2,535 $ 14,392 $ (12,234 ) $ 2,158 Intangible asset amortization expense for the three months ended September 30, 2018 and 2017 was $0.4 million and $0.9 million , respectively. Intangible asset amortization expense for the nine months ended September 30, 2018 and 2017 was $1.2 million and $3.9 million , respectively. The Company's estimated future amortization expense related to intangible assets as of September 30, 2018 , for the years ended December 31 is as follows: Estimated Future Amortization 2018 $ 281 2019 860 2020 538 2021 363 2022 246 Thereafter 247 Total $ 2,535

Other Non-Current Liabilities

Other Non-Current Liabilities	9 Months Ended
	Sep. 30, 2018
Other Liabilities Disclosure [Abstract]
Other Non-Current Liabilities	Other Current Assets and Liabilities and Non-Current Liabilities The components of other current assets are as follows: September 30, December 31, Contract assets $ 21,989 $ 3,538 Other 7,794 8,082 Total other current assets $ 29,783 $ 11,620 The components of other current liabilities are as follows: September 30, December 31, Restructuring charges $ 2,124 $ 13,023 Other 33,003 27,323 Total other current liabilities $ 35,127 $ 40,346 The components of other non-current liabilities are as follows: September 30, December 31, Premise related costs $ 16,180 $ 18,360 Accrued earnout payments 3,373 3,076 Restructuring charges — 10 Other 2,216 2,151 Total other non-current liabilities $ 21,769 $ 23,597

Line of Credit

Line of Credit	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Line of Credit	Line of Credit On June 30, 2015 , the Company entered into a Second Amended and Restated Credit Agreement (the “Restated Credit Agreement”). Pursuant to the Restated Credit Agreement, the Company replaced its existing facility with a single senior unsecured revolving line of credit with an aggregate commitment of up to $100 million , which includes a sublimit of $25 million for letters of credit, and a $50 million expansion feature. The Restated Credit Agreement will mature on June 30, 2020 . Borrowings under the Restated Credit Agreement bear interest at the Company’s election at the existing Alternate Base Rate (as defined in the Restated Credit Agreement) or Adjusted LIBOR Rate (as defined in the Restated Credit Agreement) plus a spread as determined by the Company’s leverage ratio. Borrowings under the Restated Credit Agreement may be used for working capital, capital expenditures, permitted acquisitions (as defined in the Restated Credit Agreement) and for other general corporate purposes of the Company and its subsidiaries. The obligations under the Restated Credit Agreement are guaranteed by certain of the Company’s subsidiaries. During the nine months ended September 30, 2018, the Company borrowed $20.0 million under the Restated Credit Agreement and elected the Adjusted LIBOR Rate. The Company subsequently repaid $20.0 million during the nine months ended September 30, 2018. As of September 30, 2018 and December 31, 2017, the Company had no outstanding borrowings under the Restated Credit Agreement. As of September 30, 2018, the Company was in compliance with the financial and other covenants in the Restated Credit Agreement, and no event of default existed.

Stock-based Compensation

Stock-based Compensation	9 Months Ended
	Sep. 30, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-based Compensation	Stock-Based Compensation The Company’s 2012 Amended and Restated Heidrick & Struggles GlobalShare Program (the “2012 Program”) provides for grants of stock options, stock appreciation rights, and other stock-based awards that are valued based upon the grant date fair value of shares. These awards may be granted to directors, selected employees and independent contractors. The 2012 Program originally authorized 1,300,000 shares of Common Stock for issuance pursuant to awards under the plan. On May 22, 2014 , the stockholders of the Company approved an amendment to the 2012 Program to increase the number of shares of Common Stock reserved for issuance under the 2012 Program by 700,000 shares. On May 24, 2018 , the stockholders of the Company approved an amendment to the 2012 Program to increase the number of shares of Common Stock reserved for issuance under the 2012 Program by 850,000 shares. As of September 30, 2018 , 2,149,864 awards have been issued under the 2012 Program and 1,368,789 shares remain available for future awards, including 668,653 forfeited awards. The 2012 Program provides that no awards can be granted after May 24, 2028 . The Company measures its stock-based compensation costs based on the grant date fair value of the awards and recognizes these costs in the financial statements over the requisite service period. A summary of information with respect to stock-based compensation is as follows: Three Months Ended Nine Months Ended 2018 2017 2018 2017 Salaries and employee benefits $ 2,911 $ 199 $ 6,200 $ 3,915 General and administrative expenses — — 563 338 Income tax benefit related to stock-based compensation included in net income 771 79 1,792 1,561 Restricted Stock Units Restricted stock unit activity for the nine months ended September 30, 2018 is as follows: Number of Weighted- Outstanding on December 31, 2017 491,154 $ 21.92 Granted 297,664 34.64 Vested and converted to common stock (199,550 ) 21.66 Forfeited (70,506 ) 25.66 Outstanding on September 30, 2018 518,762 $ 28.81 As of September 30, 2018 , there was $7.8 million of pre-tax unrecognized compensation expense related to unvested restricted stock units, which is expected to be recognized over a weighted average of 2.9 years . Performance Stock Units The Company grants performance stock units to certain of its senior executives. The performance stock units are generally subject to a cliff vesting at the end of a three -year period. The vesting will vary between 0% and 200% based on the attainment of operating income goals over the three -year vesting period. The performance stock units are expensed on a straight-line basis over the three -year vesting period. Performance stock unit activity for the nine months ended September 30, 2018 is as follows: Number of Stock Units Weighted- Outstanding on December 31, 2017 185,891 $ 23.82 Granted 102,138 25.81 Vested and converted to common stock (43,361 ) 23.64 Forfeited (47,551 ) 23.87 Outstanding on September 30, 2018 197,117 $ 24.88 As of September 30, 2018 , there was $3.2 million of pre-tax unrecognized compensation expense related to unvested performance stock units, which is expected to be recognized over a weighted average of 2.0 years . Phantom Stock Units Phantom stock units are grants of phantom stock with respect to shares of the Company's common stock that are settled in cash and are subject to various restrictions, including restrictions on transferability, vesting and forfeiture provisions. Shares of phantom stock that do not vest for any reason will be forfeited by the recipient and will revert to the Company. During the three months ended September 30, 2018, phantom stock with respect to 114,118 shares of common stock were granted to certain employees of the Company and are subject to vesting over a period of four years and certain other conditions, including continued service to the Company. As a result of the cash-settlement feature of the awards, the Company considers the awards to be liability awards, which are measured at fair value at each reporting date and the vested portion of the award is recognized as a liability to the extent that the service condition is deemed probable. The fair value of the phantom stock awards as of September 30, 2018, was determined using the closing share price of the Company's common stock on that date. The Company recorded phantom stock based compensation expense of $0.4 million during the three months ended September 30, 2018. Phantom stock unit activity for the nine months ended September 30, 2018 is as follows: Number of Stock Units Outstanding on December 31, 2017 — Granted 114,118 Vested — Forfeited — Outstanding on September 30, 2018 114,118 As of September 30, 2018 , there was $3.3 million of pre-tax unrecognized compensation expense related to unvested phantom stock units, which is expected to be recognized over a weighted average of 3.8 years .

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The Company reported income before taxes of $23.2 million and an income tax provision of $6.7 million for the three months ended September 30, 2018 . The Company reported income before taxes of $14.3 million and an income tax provision of $6.1 million for the three months ended September 30, 2017 . The effective tax rates for the three months ended September 30, 2018 and 2017 , were 29.0% and 42.7% , respectively. The effective tax rate for the three months ended September 30, 2018 was impacted by one-time items and the Tax Cuts and Jobs Act. The effective tax rate for the three months ended September 30, 2017 was impacted by the deferred tax effect on the long-lived assets and goodwill impairment and the inability to recognize losses in certain jurisdictions. The Company reported income before taxes of $54.5 million and an income tax provision of $16.4 million for the nine months ended September 30, 2018 . The Company reported loss before taxes of $10.3 million and an income tax benefit of $0.9 million for the nine months ended September 30, 2017 . The effective tax rates for the nine months ended September 30, 2018 and 2017 , were 30.1% and 8.7% , respectively. The effective tax rate for the nine months ended September 30, 2018 was impacted by one-time items and the Tax Cuts and Jobs Act. The effective tax rate for the nine months ended September 30, 2017 was impacted by the non-deductibility of the employee benefit tax settlement, the deferred tax effect on the long-lived assets and goodwill impairment and the inability to recognize losses in certain jurisdictions. The Company estimates that its effective tax rate for the year ended December 31, 2018 , will be between 31% and 36% . The full year effective rate for 2018 is primarily the result of one-time items and the Tax Cuts and Jobs Act. On December 22, 2017 , the SEC staff issued Staff Accounting Bulletin No. 118 (“SAB 118”) to address the application of U.S. GAAP in situations when a registrant does not have the necessary information available, prepared or analyzed (including computations) in reasonable detail to complete the accounting for certain income tax effects of the Tax Cuts and Jobs Act. The Company has recognized the provisional tax impacts related to the revaluation of deferred tax assets and liabilities, foreign earnings intended to be remitted, and the tax on foreign earnings intended to be remitted. The Company has included these amounts in its consolidated financial statements for the quarter ended September 30, 2018 . The ultimate impact may differ from these provisional amounts, possibly materially, due to, among other things, additional analysis, changes in interpretations and assumptions the Company has made, additional regulatory guidance that may be issued, and actions the Company may take as a result of the Tax Cuts and Jobs Act. The Company expects to complete the analysis and update the provisional amounts within the measurement period in accordance with SAB 118.

Changes in Accumulated Other Co

Changes in Accumulated Other Comprehensive Income	9 Months Ended
	Sep. 30, 2018
Equity [Abstract]
Changes in Accumulated Other Comprehensive Income	Changes in Accumulated Other Comprehensive Income The changes in Accumulated other comprehensive income (“AOCI”) by component for the nine months ended September 30, 2018 is summarized below: Available- Foreign Pension AOCI Balance at December 31, 2017 $ 6,089 $ 9,143 $ (1,917 ) $ 13,315 Other comprehensive income before classification, net of tax — (3,107 ) — (3,107 ) Amount reclassified from AOCI — — — — Net current period other comprehensive income — (3,107 ) — (3,107 ) Adoption of accounting standards (1) (6,089 ) — — (6,089 ) Balance at September 30, 2018 $ — $ 6,036 $ (1,917 ) $ 4,119 (1) Upon adoption of ASC 2016-01, unrealized gains (losses) on available for sale securities were reclassified from AOCI to retained earnings.

Segment Information

Segment Information	9 Months Ended
	Sep. 30, 2018
Segment Reporting [Abstract]
Segment Information	Segment Information In 2018, the Company completed the integration of its Leadership Consulting and Culture Shaping businesses into one combined service offering, Heidrick Consulting. In conjunction with the integration, the Company reorganized its Management Committee, which the Company considers to be its chief operating decision maker, so as to regularly assess performance and make resource allocations decisions for the Heidrick Consulting business. Therefore, the Company now reports Leadership Consulting and Culture Shaping as one operating segment, Heidrick Consulting. In conjunction with the change in operating segments, the Company modified its corporate cost allocation methodology. Previously reported operating segment results for the three and nine months ended September 30, 2017 , have been recast to conform to the new operating segment structure and corporate cost allocation methodology. The Company currently operates its executive search business in the Americas, Europe (which includes Africa), and Asia Pacific (which includes the Middle East), and operates its Heidrick Consulting business globally. For segment purposes, reimbursements of out-of-pocket expenses classified as revenue and other operating income are reported separately and, therefore, are not included in the results of each segment. The Company believes that analyzing trends in revenue before reimbursements (net revenue), analyzing operating expenses as a percentage of net revenue, and analyzing operating income, more appropriately reflect its core operations. The revenue and operating income (loss) by segment are as follows: Three Months Ended Nine Months Ended 2018 2017 2018 2017 Revenue Executive Search Americas $ 106,504 $ 88,254 $ 295,499 $ 248,442 Europe 37,452 33,994 110,419 90,534 Asia Pacific 28,095 21,865 78,460 64,162 Total Executive Search 172,051 144,113 484,378 403,138 Heidrick Consulting 15,537 15,687 46,340 48,882 Revenue before reimbursements (net revenue) 187,588 159,800 530,718 452,020 Reimbursements 4,753 4,665 13,970 13,740 Total revenue $ 192,341 $ 164,465 $ 544,688 $ 465,760 Three Months Ended Nine Months Ended 2018 2017 2018 2017 Operating income (loss) Executive Search Americas $ 23,341 $ 21,140 $ 69,988 $ 60,958 Europe 904 3,047 6,453 4,207 Asia Pacific 6,414 369 13,608 3,966 Total Executive Search 30,659 24,556 90,049 69,131 Heidrick Consulting (1,761 ) (2,625 ) (10,988 ) (49,849 ) Total segment operating income 28,898 21,931 79,061 19,282 Global Operations Support (8,315 ) (7,909 ) (26,896 ) (27,033 ) Total operating income (loss) $ 20,583 $ 14,022 $ 52,165 $ (7,751 )

Guarantees

Guarantees	9 Months Ended
	Sep. 30, 2018
Guarantees [Abstract]
Guarantees	Guarantees The Company has issued cash collateralized bank guarantees and letter of credit-backed bank guarantees supporting certain obligations, primarily the payment of office lease obligations and business license requirements for certain of its subsidiaries in Europe and Asia Pacific. The bank guarantees were made to secure the respective agreements and are for the terms of the agreements, which extend through 2023 . For each bank guarantee issued, the Company would have to perform under the guarantee if the subsidiary defaults on a lease payment. The maximum amount of undiscounted payments the Company would be required to make in the event of default on all outstanding guarantees is approximately $2.6 million as of September 30, 2018 . The Company has not accrued for these arrangements as no event of default exists or is expected to exist.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2018
Loss Contingencies [Line Items]
Contingencies Disclosure [Text Block]	Commitments and Contingencies Litigation The Company has contingent liabilities from various pending claims and litigation matters arising in the ordinary course of the Company’s business, some of which involve claims for damages that are substantial in amount. Some of these matters are covered by insurance. Based upon information currently available, the Company believes the ultimate resolution of such claims and litigation will not have a material adverse effect on its financial condition, results of operations or liquidity.

Subsequent Event

Subsequent Event	9 Months Ended
	Sep. 30, 2018
Subsequent Event [Line Items]
Subsequent Events [Text Block]	19. Subsequent Event On October 26, 2018, the Company entered into a new Credit Agreement (the "2018 Credit Agreement") to replace the Second Amended and Restated Credit Agreement executed on June 30, 2015. The 2018 Credit Agreement provides the Company with a senior unsecured revolving line of credit with an aggregate commitment of $175 million , which includes a sublimit of $25 million for letters of credit, and a $10 million swingline loan sublimit. The agreement also includes a $75 million expansion feature. Borrowings under the 2018 Credit Agreement bear interest at the Company's election of the Alternate Base Rate (as defined in the 2018 Credit Agreement) or Adjusted LIBOR (as defined in the 2018 Credit Agreement) plus a spread as determined by the Company’s leverage ratio. The 2018 Credit Agreement will mature in October 2023. There are no outstanding borrowings under the 2018 Credit Agreement as of the date of filing this Quarterly Report on Form 10-Q.

Restructuring (Notes)

Restructuring (Notes)	9 Months Ended
	Sep. 30, 2018
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Activities Disclosure [Text Block]	Restructuring Restructuring Charges In 2017, the Company recorded restructuring charges of $15.7 million in connection with initiatives to reduce overall costs and improve operational efficiencies. The primary components of the restructuring include: the elimination of two executive officer roles for a flatter leadership structure, a workforce reduction as the firm aligns its support resources to better meet operational needs and recognize synergies with the combination of Leadership Consulting and Culture Shaping, a reduction of the firm’s real estate expenses and support costs by consolidating or closing three of its locations across its global footprint, and the acceleration of future expenses under certain contractual obligations. These charges consist of $13.1 million of employee-related costs, including severance associated with reductions in our workforce of 251 employees globally, $2.3 million of other professional and consulting fees and $0.3 million of expenses associated with closing three office locations. Changes to the accrual for restructuring charges for the nine months ended September 30, 2018 , are as follows: Employee Related Office Related Other Total Outstanding on December 31, 2017 $ 11,866 $ 148 $ 1,011 $ 13,025 Cash payments (7,940 ) (248 ) (981 ) (9,169 ) Other (1,793 ) 100 27 (1,666 ) Exchange rate fluctuations (59 ) — (7 ) (66 ) Outstanding on September 30, 2018 $ 2,074 $ — $ 50 $ 2,124

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2018
Summary of Significant Accounting Policies [Abstract]
Revenue Recognition, Policy [Policy Text Block]	Revenue Recognition As a result of the adoption of ASU 2014-09, Revenue from Contracts with Customers, the Company's accounting policy for revenue recognition has been updated. See Note 3 , Revenue.
Cash and Cash Equivalents, Restricted Cash and Cash Equivalents, Policy [Policy Text Block]	Restricted Cash The Company has lease agreements and business licenses with terms that require the Company to restrict cash through the termination dates of the agreements. Current and non-current restricted cash is included in Other current assets and Other non-current assets , respectively, in the Condensed Consolidated Balance Sheets. The following table provides a reconciliation of the cash and cash equivalents between the Condensed Consolidated Balance Sheets and the Condensed Consolidated Statement of Cash Flows as of September 30, 2018 and 2017 , and December 31, 2017 and 2016 : September 30, December 31, 2018 2017 2017 2016 Cash and cash equivalents $ 164,216 $ 105,718 $ 207,534 $ 165,011 Restricted cash included within other current assets 598 265 526 139 Restricted cash included within other non-current assets — 355 102 419 Total cash, cash equivalents and restricted cash $ 164,814 $ 106,338 $ 208,162 $ 165,569
Reclassification, Policy [Policy Text Block]	Reclassifications Certain prior year amounts have been recast as a result of the change in the Company's operating segments and adoption of ASU No. 2016-18, Statement of Cash Flows: Restricted Cash. The reclassifications had no impact on net income, net cash flows or stockholders' equity.
Earnings Per Share, Policy [Policy Text Block]	Earnings per Common Share Basic earnings per common share is computed by dividing net income by weighted average common shares outstanding for the period. Diluted earnings per share reflect the potential dilution that could occur if securities or other contracts to issue common stock were exercised or converted. Common equivalent shares are excluded from the determination of diluted earnings per share in periods in which they have an anti-dilutive effect. The following table sets forth the computation of basic and diluted earnings per share: Three Months Ended Nine Months Ended 2018 2017 2018 2017 Net income (loss) $ 16,469 $ 8,171 $ 38,100 $ (9,427 ) Weighted average shares outstanding: Basic 18,954 18,781 18,905 18,720 Effect of dilutive securities: Restricted stock units 278 187 345 — Performance stock units 169 48 194 — Diluted 19,401 19,016 19,444 18,720 Basic earnings per share $ 0.87 $ 0.44 $ 2.02 $ (0.50 ) Diluted earnings per share $ 0.85 $ 0.43 $ 1.96 $ (0.50 ) Weighted average restricted stock units and performance stock units outstanding that could be converted into approximately 327,000 and 80,000 common shares, respectively, for the nine months ended September 30, 2017, were not included in the computation of diluted earnings per share because the effects would be anti-dilutive.
New Accounting Pronouncements, Policy [Policy Text Block]	Recently Issued Financial Accounting Standards In February 2018, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") No. 2018-02, Income Statement - Reporting Comprehensive Income, intended to improve the usefulness of information reported as a result of the Tax Cuts and Jobs Act. The new guidance allows a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the Tax Cuts and Jobs Act. ASU 2018-02 is effective for interim and annual periods beginning after December 15, 2018, with early adoption permitted. The Company is currently evaluating the impact of this accounting guidance. The effect is not known or reasonably estimable at this time. In February 2016, the FASB issued ASU No. 2016-02, Leases, intended to improve financial reporting about leasing transactions. The new guidance will require entities that lease assets to recognize on their balance sheets the assets and liabilities for the rights and obligations created by those leases and to disclose key information about the leasing arrangements. ASU 2016-02 is effective for interim and annual periods beginning after December 15, 2018, with early adoption permitted. The guidance requires lessees and lessors to recognize and measure leases at the beginning of the earliest period presented using a modified retrospective approach. In July 2018, the FASB issued ASU No. 2018-11, Leases, intended to provide transition relief on comparative reporting at adoption. The ASU allows companies to present prior periods under current GAAP (Topic 840), rather than restating all periods presented under the new requirements of ASU No. 2016-02. ASU No. 2018-11 also eliminated the requirement that companies separate non-lease and lease components in a contract, and allows companies to account for those components as a single lease. The Company will adopt the guidance on January 1, 2019 using the modified retrospective method without restatement of the prior periods. As such, prior periods will continue to be presented under the existing ASC 840 lease accounting guidance. The Company is currently performing its evaluation of ASU 2016-02 and ASU 2018-11. The adoption of the guidance will have a material impact on the Company's Consolidated Balance Sheets with respect to recording a right-of-use asset and lease liability for each of the Company's leases. The Company's lease portfolio is primarily comprised of office leases, which are currently classified as operating leases and will continue to be classified as operating leases under the new guidance. The Company does not anticipate a significant change in expense recognition as it relates to the new guidance. Recently Adopted Financial Accounting Standards On January 1, 2018, the Company adopted ASU No. 2017-09, Compensation - Stock Compensation, Scope of Modification Accounting, which is intended to provide clarity and reduce both diversity in practice, cost and complexity when implementing a change in the terms or conditions of a share-based payment award. ASU 2017-09 requires that an entity should account for the effects of a modification unless the fair value, vesting conditions and whether the award is classified as a liability instrument or an equity instrument remain unchanged in the modification. The adoption of this guidance did not have an impact on the Company's financial statements. The future impact of this accounting guidance will be dependent on future modification events including the number of awards modified. On January 1, 2018, the Company adopted ASU No. 2017-07, Compensation - Retirement Benefits: Improving the Presentation of Net Periodic Pension Cost and Net Periodic Post-retirement Benefit Cost, which is intended to improve the consistency, transparency and usefulness of net benefit cost disclosures. ASU 2017-07 requires that an employer report the service cost component of net benefit cost in the same line item or items as other compensation costs arising from services rendered by the pertinent employees during the period. Additionally, the other components of net benefit costs are required to be presented in the income statement separately from the service cost component and outside a subtotal of income from operations. The adoption of this guidance did not have an impact on the Company's financial statements. On January 1, 2018, the Company adopted ASU No. 2016-18, Statement of Cash Flows: Restricted Cash, which requires that the statement of cash flows explain the change during the period in the total of cash, cash equivalents and amounts generally described as restricted cash or restricted cash equivalents. Therefore, amounts generally described as restricted cash should be included with cash and cash equivalents when reconciling the beginning of period and end of period total amounts shown on the statement of cash flows. The adoption of this guidance increased the Company's beginning and ending balances of cash, cash equivalents and restricted cash in the Condensed Consolidated Statement of Cash Flows by approximately $0.6 million for each period presented. Changes in the Company's restricted cash balances between periods are immaterial. On January 1, 2018, the Company adopted ASU No. 2016-15, Statement of Cash Flows: Classification of Certain Cash Receipts and Cash Payments, which is intended to reduce diversity in practice as to how certain cash receipts and cash payments should be presented and classified. The adoption of this guidance did not have an impact on the Company's financial statements. On January 1, 2018, the Company adopted ASU 2016-01, Financial Instruments: Recognition and Measurement of Financial Assets and Financial Liabilities, which addresses certain aspects of recognition, measurement, presentation and disclosure of financial instruments including the recognition of unrealized changes in fair value within net income. The adoption of this guidance resulted in a reclassification of accumulated unrealized gains of approximately $6.1 million from accumulated other comprehensive income to retained earnings. The impact of the adoption of this guidance on the Company's Condensed Consolidated Statement of Comprehensive Income for the nine months ended September 30, 2018, was not material. The comparative periods have not been restated and continue to be reported under the accounting standards in effect for those periods. On January 1, 2018, the Company adopted ASU No. 2014-09, Revenue from Contracts with Customers, using the modified retrospective method. The Company applied the guidance to all contracts that were not complete as of the adoption date. The guidance requires that an entity recognizes revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the Company expects to be entitled in exchange for these goods or services. The Company recognized the cumulative effect of initially applying the new guidance as an adjustment to the opening balance of retained earnings. The comparative periods have not been restated and continue to be reported under the accounting standards in effect for those periods. Impacts on Financial Statements of Recently Adopted Financial Accounting Standards The cumulative effect of the changes made to our Condensed Consolidated Balance Sheet as of January 1, 2018 as a result of the adoption of ASU 2014-09, Revenue from Contracts with Customers, and ASU 2016-01, Financial Instruments: Recognition and Measurement of Financial Assets and Financial Liabilities was as follows: December 31, ASU 2014-09 Adjustments ASU 2016-01 Adjustments January 1, Current assets Other current assets $ 11,620 $ 14,689 $ — $ 26,309 Total current assets 343,790 14,689 — 358,479 Non-current assets Deferred income taxes 35,402 (3,099 ) — 32,303 Total non-current assets 243,414 (3,099 ) — 240,315 Total assets $ 587,204 $ 11,590 $ — $ 598,794 Current liabilities Deferred revenue 31,272 (1,059 ) — 30,213 Other current liabilities 40,346 3,695 — 44,041 Total current liabilities 265,792 2,636 — 268,428 Total liabilities $ 374,499 $ 2,636 $ — $ 377,135 Stockholders' equity Retained earnings (deficit) (716 ) 8,954 6,089 14,327 Accumulated other comprehensive income 13,315 — (6,089 ) 7,226 Total stockholders’ equity 212,705 8,954 — 221,659 Total liabilities and stockholders’ equity $ 587,204 $ 11,590 $ — $ 598,794 The impact of ASU 2014-09, Revenue from Contracts with Customers, on our Condensed Consolidated Balance Sheet as of September 30, 2018 was as follows: September 30, 2018 As Reported Balances Without Adoption of ASU 2014-09 Effect of Adoption Higher/(Lower) Current assets Other current assets $ 29,783 $ 12,678 $ 17,105 Total current assets 382,952 365,847 17,105 Non-current assets Deferred income taxes 32,320 35,419 (3,099 ) Total non-current assets 249,904 253,003 (3,099 ) Total assets $ 632,856 $ 618,850 $ 14,006 Current liabilities Accrued salaries and employee benefits 177,930 176,984 946 Deferred revenue 42,870 43,531 (661 ) Other current liabilities 35,127 30,760 4,367 Income taxes payable 7,866 7,746 120 Total current liabilities 272,772 268,000 4,772 Total liabilities $ 379,023 $ 374,251 $ 4,772 Stockholders' equity Retained earnings (deficit) 44,854 35,620 9,234 Total stockholders’ equity 253,833 244,599 9,234 Total liabilities and stockholders’ equity $ 632,856 $ 618,850 $ 14,006 The impact of ASU 2014-09, Revenue from Contracts with Customers, on our Condensed Consolidated Statement of Comprehensive Income for the three and nine months ended September 30, 2018 was as follows: Three Months Ended September 30, 2018 Nine Months Ended September 30, 2018 As Reported Balances Without Adoption of ASU 2014-09 Effect of Adoption Higher/(Lower) As Reported Balances Without Adoption of ASU 2014-09 Effect of Adoption Higher/(Lower) Revenue Revenue before reimbursements (net revenue) $ 187,588 $ 187,720 $ (132 ) $ 530,718 $ 529,372 $ 1,346 Reimbursements 4,753 4,753 — 13,970 13,970 — Total revenue 192,341 192,473 (132 ) 544,688 543,342 1,346 Operating expenses Salaries and employee benefits 133,933 134,017 (84 ) 373,021 372,075 946 General and administrative expenses 33,072 33,072 — 105,532 105,532 — Reimbursed expenses 4,753 4,753 — 13,970 13,970 — Total operating expenses 171,758 171,842 (84 ) 492,523 491,577 946 Operating income 20,583 20,631 (48 ) 52,165 51,765 400 Non-operating income (expense) Interest, net 259 259 — 496 496 — Other, net 2,345 2,345 — 1,849 1,849 — Net non-operating income (expense) 2,604 2,604 — 2,345 2,345 — Income before income taxes 23,187 23,235 (48 ) 54,510 54,110 400 Provision for income taxes 6,718 6,736 (18 ) 16,410 16,290 120 Net income $ 16,469 $ 16,499 $ (30 ) $ 38,100 $ 37,820 $ 280 Basic earnings per share $ 0.87 $ 0.87 $ — $ 2.02 $ 2.00 $ 0.02 Diluted earnings per share $ 0.85 $ 0.85 $ — $ 1.96 $ 1.95 $ 0.01 The impact of ASU 2014-09, Revenue from Contracts with Customers, on our Condensed Consolidated Statement of Cash Flows for the nine months ended September 30, 2018 was as follows: Nine Months Ended September 30, 2018 As Reported Balances Without Adoption of ASU 2014-09 Effect of Adoption Higher/(Lower) Cash flows - operating activities Net income $ 38,100 $ 37,820 $ 280 Changes in assets and liabilities, net of effects of acquisitions: Accrued expenses 3,834 (1,479 ) 5,313 Deferred revenue 185 2,843 (2,658 ) Income taxes payable, net (2,003 ) (2,123 ) 120 Other assets and liabilities, net $ (3,761 ) $ (705 ) $ (3,056 )

Summary of Significant Accoun_3

Summary of Significant Accounting Policies Earnings Per Share (Tables)	9 Months Ended
	Sep. 30, 2018
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]	The following table sets forth the computation of basic and diluted earnings per share: Three Months Ended Nine Months Ended 2018 2017 2018 2017 Net income (loss) $ 16,469 $ 8,171 $ 38,100 $ (9,427 ) Weighted average shares outstanding: Basic 18,954 18,781 18,905 18,720 Effect of dilutive securities: Restricted stock units 278 187 345 — Performance stock units 169 48 194 — Diluted 19,401 19,016 19,444 18,720 Basic earnings per share $ 0.87 $ 0.44 $ 2.02 $ (0.50 ) Diluted earnings per share $ 0.85 $ 0.43 $ 1.96 $ (0.50 )

Summary of Significant Accoun_4

Summary of Significant Accounting Policies Restricted Cash (Tables)	9 Months Ended
	Sep. 30, 2018
Cash and Cash Equivalents [Abstract]
Schedule of Cash, Cash Equivalents, and Restricted Cash [Table Text Block]	The following table provides a reconciliation of the cash and cash equivalents between the Condensed Consolidated Balance Sheets and the Condensed Consolidated Statement of Cash Flows as of September 30, 2018 and 2017 , and December 31, 2017 and 2016 : September 30, December 31, 2018 2017 2017 2016 Cash and cash equivalents $ 164,216 $ 105,718 $ 207,534 $ 165,011 Restricted cash included within other current assets 598 265 526 139 Restricted cash included within other non-current assets — 355 102 419 Total cash, cash equivalents and restricted cash $ 164,814 $ 106,338 $ 208,162 $ 165,569

Summary of Significant Accoun_5

Summary of Significant Accounting Policies Cumulative Effect Adjustments (Tables)	9 Months Ended
	Sep. 30, 2018
Cumulative Effect Adjustments [Table Text Block]	The cumulative effect of the changes made to our Condensed Consolidated Balance Sheet as of January 1, 2018 as a result of the adoption of ASU 2014-09, Revenue from Contracts with Customers, and ASU 2016-01, Financial Instruments: Recognition and Measurement of Financial Assets and Financial Liabilities was as follows: December 31, ASU 2014-09 Adjustments ASU 2016-01 Adjustments January 1, Current assets Other current assets $ 11,620 $ 14,689 $ — $ 26,309 Total current assets 343,790 14,689 — 358,479 Non-current assets Deferred income taxes 35,402 (3,099 ) — 32,303 Total non-current assets 243,414 (3,099 ) — 240,315 Total assets $ 587,204 $ 11,590 $ — $ 598,794 Current liabilities Deferred revenue 31,272 (1,059 ) — 30,213 Other current liabilities 40,346 3,695 — 44,041 Total current liabilities 265,792 2,636 — 268,428 Total liabilities $ 374,499 $ 2,636 $ — $ 377,135 Stockholders' equity Retained earnings (deficit) (716 ) 8,954 6,089 14,327 Accumulated other comprehensive income 13,315 — (6,089 ) 7,226 Total stockholders’ equity 212,705 8,954 — 221,659 Total liabilities and stockholders’ equity $ 587,204 $ 11,590 $ — $ 598,794

Summary of Significant Accoun_6

Summary of Significant Accounting Policies Impact of New Accounting Pronouncements - Balance Sheet (Tables)	9 Months Ended
	Sep. 30, 2018
Impact of New Accounting Pronouncements - Balance Sheet [Table Text Block]	The impact of ASU 2014-09, Revenue from Contracts with Customers, on our Condensed Consolidated Balance Sheet as of September 30, 2018 was as follows: September 30, 2018 As Reported Balances Without Adoption of ASU 2014-09 Effect of Adoption Higher/(Lower) Current assets Other current assets $ 29,783 $ 12,678 $ 17,105 Total current assets 382,952 365,847 17,105 Non-current assets Deferred income taxes 32,320 35,419 (3,099 ) Total non-current assets 249,904 253,003 (3,099 ) Total assets $ 632,856 $ 618,850 $ 14,006 Current liabilities Accrued salaries and employee benefits 177,930 176,984 946 Deferred revenue 42,870 43,531 (661 ) Other current liabilities 35,127 30,760 4,367 Income taxes payable 7,866 7,746 120 Total current liabilities 272,772 268,000 4,772 Total liabilities $ 379,023 $ 374,251 $ 4,772 Stockholders' equity Retained earnings (deficit) 44,854 35,620 9,234 Total stockholders’ equity 253,833 244,599 9,234 Total liabilities and stockholders’ equity $ 632,856 $ 618,850 $ 14,006

Summary of Significant Accoun_7

Summary of Significant Accounting Policies Impact of New Accounting Pronouncements - Income Statement (Tables)	9 Months Ended
	Sep. 30, 2018
Impact of New Accounting Pronouncements - Income Statement [Table Text Block]	The impact of ASU 2014-09, Revenue from Contracts with Customers, on our Condensed Consolidated Statement of Comprehensive Income for the three and nine months ended September 30, 2018 was as follows: Three Months Ended September 30, 2018 Nine Months Ended September 30, 2018 As Reported Balances Without Adoption of ASU 2014-09 Effect of Adoption Higher/(Lower) As Reported Balances Without Adoption of ASU 2014-09 Effect of Adoption Higher/(Lower) Revenue Revenue before reimbursements (net revenue) $ 187,588 $ 187,720 $ (132 ) $ 530,718 $ 529,372 $ 1,346 Reimbursements 4,753 4,753 — 13,970 13,970 — Total revenue 192,341 192,473 (132 ) 544,688 543,342 1,346 Operating expenses Salaries and employee benefits 133,933 134,017 (84 ) 373,021 372,075 946 General and administrative expenses 33,072 33,072 — 105,532 105,532 — Reimbursed expenses 4,753 4,753 — 13,970 13,970 — Total operating expenses 171,758 171,842 (84 ) 492,523 491,577 946 Operating income 20,583 20,631 (48 ) 52,165 51,765 400 Non-operating income (expense) Interest, net 259 259 — 496 496 — Other, net 2,345 2,345 — 1,849 1,849 — Net non-operating income (expense) 2,604 2,604 — 2,345 2,345 — Income before income taxes 23,187 23,235 (48 ) 54,510 54,110 400 Provision for income taxes 6,718 6,736 (18 ) 16,410 16,290 120 Net income $ 16,469 $ 16,499 $ (30 ) $ 38,100 $ 37,820 $ 280 Basic earnings per share $ 0.87 $ 0.87 $ — $ 2.02 $ 2.00 $ 0.02 Diluted earnings per share $ 0.85 $ 0.85 $ — $ 1.96 $ 1.95 $ 0.01

Summary of Significant Accoun_8

Summary of Significant Accounting Policies Impact of New Accounting Pronouncements - Cash Flow (Tables)	9 Months Ended
	Sep. 30, 2018
Impact of New Accounting Pronouncements - Cash Flow [Table Text Block]	The impact of ASU 2014-09, Revenue from Contracts with Customers, on our Condensed Consolidated Statement of Cash Flows for the nine months ended September 30, 2018 was as follows: Nine Months Ended September 30, 2018 As Reported Balances Without Adoption of ASU 2014-09 Effect of Adoption Higher/(Lower) Cash flows - operating activities Net income $ 38,100 $ 37,820 $ 280 Changes in assets and liabilities, net of effects of acquisitions: Accrued expenses 3,834 (1,479 ) 5,313 Deferred revenue 185 2,843 (2,658 ) Income taxes payable, net (2,003 ) (2,123 ) 120 Other assets and liabilities, net $ (3,761 ) $ (705 ) $ (3,056 )

Revenue (Tables)

Revenue (Tables)	9 Months Ended
	Sep. 30, 2018
Unbilled Receivables, Contract Assets and Liabilities [Line Items]
Unbilled Receivables, Contract Assets and Liabilities [Table Text Block]	The following table outlines the changes in our contract asset and liability balances during the period: January 1, September 30, Variance Contract assets Unbilled receivables $ 5,487 $ 7,655 $ 2,168 Contract assets 12,398 14,334 1,936 Contract liabilities Deferred revenue $ 30,370 $ 42,870 $ 12,500

Allowance for Doubtful Accoun_2

Allowance for Doubtful Accounts (Tables)	9 Months Ended
	Sep. 30, 2018
Schedule of Allowance for Doubtful Accounts Receivable [Line Items]
Schedule of Allowance for Doubtful Accounts Receivable [Table Text Block]	The activity of the allowance for doubtful accounts is as follows: Balance at December 31, 2017 $ 2,534 Provision charged to income 3,899 Write-offs, net of recoveries (1,203 ) Foreign currency translation (99 ) Balance at September 30, 2018 $ 5,131

Property and Equipment, net (Ta

Property and Equipment, net (Tables)	9 Months Ended
	Sep. 30, 2018
Property, Plant and Equipment [Abstract]
Components of Company's Property and Equipment	The components of the Company’s property and equipment are as follows: September 30, December 31, Leasehold improvements $ 47,863 $ 48,216 Office furniture, fixtures and equipment 17,960 17,732 Computer equipment and software 27,427 28,300 Property and equipment, gross 93,250 94,248 Accumulated depreciation (57,759 ) (54,734 ) Property and equipment, net $ 35,491 $ 39,514

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Levels of Inputs Used to Measure Fair Value of Assets	The following tables provide a summary of the fair value measurements at September 30, 2018 , and December 31, 2017 , for each major category of assets and liabilities measured at fair value on a recurring basis: Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Balance at September 30, 2018 U.S. non-qualified deferred compensation plan $ 21,013 $ — $ — $ 21,013 Assets designated for retirement and pension plans — 17,965 — 17,965 Pension benefit obligation — (23,089 ) — (23,089 ) Acquisition earnout accruals — — (10,490 ) (10,490 ) $ 21,013 $ (5,124 ) $ (10,490 ) $ 5,399 Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Balance at December 31, 2017 U.S. non-qualified deferred compensation plan $ 21,319 $ — $ — $ 21,319 Assets designated for retirement and pension plans — 18,590 — 18,590 Pension benefit obligation — (23,886 ) — (23,886 ) Acquisition earnout accruals — — (7,213 ) (7,213 ) $ 21,319 $ (5,296 ) $ (7,213 ) $ 8,810
Reconciliation of Beginning and Ending Balance of Level 3 Assets and Liabilities	The following table provides a reconciliation of the beginning and ending balance of Level 3 assets and liabilities for the nine months ended September 30, 2018 : Acquisition Balance at December 31, 2017 $ (7,213 ) Acquisition earnouts (Note 8) (3,054 ) Earnout accretion (963 ) Philosophy IB earnout adjustment (1) 436 Foreign currency translation 304 Balance at September 30, 2018 $ (10,490 )

Goodwill and Other Intangible_2

Goodwill and Other Intangible Assets (Tables)	9 Months Ended
	Sep. 30, 2018
Goodwill by Segment [Line Items]
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]	The Company's estimated future amortization expense related to intangible assets as of September 30, 2018 , for the years ended December 31 is as follows: Estimated Future Amortization 2018 $ 281 2019 860 2020 538 2021 363 2022 246 Thereafter 247 Total $ 2,535
Changes in Carrying Amount of Goodwill by Segment	Changes in the carrying amount of goodwill by segment for the nine months ended September 30, 2018 , are as follows: Executive Search Heidrick Consulting Americas Europe Asia Pacific Total Gross goodwill at December 31, 2017 $ 88,690 $ 44,407 $ 9,302 $ 36,257 $ 178,656 Accumulated impairment — (23,507 ) — (36,257 ) (59,764 ) Net goodwill at December 31, 2017 88,690 20,900 9,302 — 118,892 Amrop acquisition — 5,102 — — 5,102 Foreign currency translation (95 ) (908 ) (546 ) — (1,549 ) Net goodwill at September 30, 2018 $ 88,595 $ 25,094 $ 8,756 $ — $ 122,445
Summary of Other Intangible Assets Net by Segment	The Company’s other intangible assets, net by segment, are as follows: September 30, December 31, 2017 Executive Search Americas $ 73 $ 252 Europe 2,378 1,799 Asia Pacific 84 107 Total Executive Search 2,535 2,158 Heidrick Consulting — — Total other intangible assets, net $ 2,535 $ 2,158
Carrying Amount of Amortizable Intangible Assets and Related Accumulated Amortization	The carrying amount of amortizable intangible assets and the related accumulated amortization are as follows: Weighted September 30, 2018 December 31, 2017 Gross Carrying Amount Accumulated Amortization Net Carrying Amount Gross Carrying Amount Accumulated Amortization Net Carrying Amount Client relationships 6.8 $ 16,053 $ (13,518 ) $ 2,535 $ 13,703 $ (11,612 ) $ 2,091 Trade name 0.0 443 (443 ) — 459 (459 ) — Non-compete 0.0 222 (222 ) — 230 (163 ) 67 Total intangible assets 6.8 $ 16,718 $ (14,183 ) $ 2,535 $ 14,392 $ (12,234 ) $ 2,158

Goodwill and Other Intangible_3

Goodwill and Other Intangible Assets Goodwill by Segment (Tables)	9 Months Ended
	Sep. 30, 2018
Goodwill by Segment [Line Items]
Goodwill by Segment [Table Text Block]	The Company's goodwill by segment is as follows: September 30, December 31, 2017 Executive Search Americas $ 88,595 $ 88,690 Europe 48,601 44,407 Asia Pacific 8,756 9,302 Total Executive Search 145,952 142,399 Heidrick Consulting 36,257 36,257 Goodwill, gross 182,209 178,656 Accumulated impairment (59,764 ) (59,764 ) Goodwill, net $ 122,445 $ 118,892

Goodwill and Other Intangible_4

Goodwill and Other Intangible Assets Goodwill, Carrying Amount (Tables)	9 Months Ended
	Sep. 30, 2018
Goodwill [Line Items]
Goodwill, Impaired, Accumulated Impairment Loss	Changes in the carrying amount of goodwill by segment for the nine months ended September 30, 2018 , are as follows: Executive Search Heidrick Consulting Americas Europe Asia Pacific Total Gross goodwill at December 31, 2017 $ 88,690 $ 44,407 $ 9,302 $ 36,257 $ 178,656 Accumulated impairment — (23,507 ) — (36,257 ) (59,764 ) Net goodwill at December 31, 2017 88,690 20,900 9,302 — 118,892 Amrop acquisition — 5,102 — — 5,102 Foreign currency translation (95 ) (908 ) (546 ) — (1,549 ) Net goodwill at September 30, 2018 $ 88,595 $ 25,094 $ 8,756 $ — $ 122,445

Other Non-Current Liabilities (

Other Non-Current Liabilities (Tables)	9 Months Ended
	Sep. 30, 2018
Other Liabilities Disclosure [Abstract]
Components of Other Non-Current Liabilities	The components of other non-current liabilities are as follows: September 30, December 31, Premise related costs $ 16,180 $ 18,360 Accrued earnout payments 3,373 3,076 Restructuring charges — 10 Other 2,216 2,151 Total other non-current liabilities $ 21,769 $ 23,597

Other Non-Current Liabilities O

Other Non-Current Liabilities Other Current Assets (Tables)	9 Months Ended
	Sep. 30, 2018
Other current assets [Line Items]
Schedule of Other Current Assets [Table Text Block]	The components of other current assets are as follows: September 30, December 31, Contract assets $ 21,989 $ 3,538 Other 7,794 8,082 Total other current assets $ 29,783 $ 11,620

Other Non-Current Liabilities_2

Other Non-Current Liabilities Other Current Liabilities (Tables)	9 Months Ended
	Sep. 30, 2018
Other Current Liabilities [Line Items]
Other Current Liabilities [Table Text Block]	The components of other current liabilities are as follows: September 30, December 31, Restructuring charges $ 2,124 $ 13,023 Other 33,003 27,323 Total other current liabilities $ 35,127 $ 40,346

Stock-based Compensation (Table

Stock-based Compensation (Tables)	9 Months Ended
	Sep. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-Based Compensation, Phantom Shares Award Outstanding Activity [Table Text Block]	Phantom stock unit activity for the nine months ended September 30, 2018 is as follows: Number of Stock Units Outstanding on December 31, 2017 — Granted 114,118 Vested — Forfeited — Outstanding on September 30, 2018 114,118
Summary of Information with Respect to Stock-based Compensation	A summary of information with respect to stock-based compensation is as follows: Three Months Ended Nine Months Ended 2018 2017 2018 2017 Salaries and employee benefits $ 2,911 $ 199 $ 6,200 $ 3,915 General and administrative expenses — — 563 338 Income tax benefit related to stock-based compensation included in net income 771 79 1,792 1,561
Restricted Stock Unit Activity	Restricted stock unit activity for the nine months ended September 30, 2018 is as follows: Number of Weighted- Outstanding on December 31, 2017 491,154 $ 21.92 Granted 297,664 34.64 Vested and converted to common stock (199,550 ) 21.66 Forfeited (70,506 ) 25.66 Outstanding on September 30, 2018 518,762 $ 28.81
Performance Stock Unit Activity	Performance stock unit activity for the nine months ended September 30, 2018 is as follows: Number of Stock Units Weighted- Outstanding on December 31, 2017 185,891 $ 23.82 Granted 102,138 25.81 Vested and converted to common stock (43,361 ) 23.64 Forfeited (47,551 ) 23.87 Outstanding on September 30, 2018 197,117 $ 24.88

Changes in Accumulated Other _2

Changes in Accumulated Other Comprehensive Income (Tables)	9 Months Ended
	Sep. 30, 2018
Equity [Abstract]
Changes in Accumulated Other Comprehensive Income ("AOCI") by Component	The changes in Accumulated other comprehensive income (“AOCI”) by component for the nine months ended September 30, 2018 is summarized below: Available- Foreign Pension AOCI Balance at December 31, 2017 $ 6,089 $ 9,143 $ (1,917 ) $ 13,315 Other comprehensive income before classification, net of tax — (3,107 ) — (3,107 ) Amount reclassified from AOCI — — — — Net current period other comprehensive income — (3,107 ) — (3,107 ) Adoption of accounting standards (1) (6,089 ) — — (6,089 ) Balance at September 30, 2018 $ — $ 6,036 $ (1,917 ) $ 4,119

Segment Information (Tables)

Segment Information (Tables)	9 Months Ended
	Sep. 30, 2018
Segment Reporting Information [Line Items]
Revenue and Operating Income (Loss), by Segment	The revenue and operating income (loss) by segment are as follows: Three Months Ended Nine Months Ended 2018 2017 2018 2017 Revenue Executive Search Americas $ 106,504 $ 88,254 $ 295,499 $ 248,442 Europe 37,452 33,994 110,419 90,534 Asia Pacific 28,095 21,865 78,460 64,162 Total Executive Search 172,051 144,113 484,378 403,138 Heidrick Consulting 15,537 15,687 46,340 48,882 Revenue before reimbursements (net revenue) 187,588 159,800 530,718 452,020 Reimbursements 4,753 4,665 13,970 13,740 Total revenue $ 192,341 $ 164,465 $ 544,688 $ 465,760 Three Months Ended Nine Months Ended 2018 2017 2018 2017 Operating income (loss) Executive Search Americas $ 23,341 $ 21,140 $ 69,988 $ 60,958 Europe 904 3,047 6,453 4,207 Asia Pacific 6,414 369 13,608 3,966 Total Executive Search 30,659 24,556 90,049 69,131 Heidrick Consulting (1,761 ) (2,625 ) (10,988 ) (49,849 ) Total segment operating income 28,898 21,931 79,061 19,282 Global Operations Support (8,315 ) (7,909 ) (26,896 ) (27,033 ) Total operating income (loss) $ 20,583 $ 14,022 $ 52,165 $ (7,751 )

Restructuring (Tables)

Restructuring (Tables)	9 Months Ended
	Sep. 30, 2018
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Activities Disclosure [Text Block]	Changes to the accrual for restructuring charges for the nine months ended September 30, 2018 , are as follows: Employee Related Office Related Other Total Outstanding on December 31, 2017 $ 11,866 $ 148 $ 1,011 $ 13,025 Cash payments (7,940 ) (248 ) (981 ) (9,169 ) Other (1,793 ) 100 27 (1,666 ) Exchange rate fluctuations (59 ) — (7 ) (66 ) Outstanding on September 30, 2018 $ 2,074 $ — $ 50 $ 2,124

Summary of Significant Accoun_9

Summary of Significant Accounting Policies (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2016
Restricted Cash and Cash Equivalents Items [Line Items]
Cash and Cash Equivalents, at Carrying Value	$ 164,216	$ 207,534	$ 105,718	$ 165,011
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	164,814	208,162	106,338	165,569
Other Current Assets [Member]
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted Cash	598	526	265	139
Other Noncurrent Assets [Member]
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted Cash	$ 0	$ 102	$ 355	$ 419

Summary of Significant Accou_10

Summary of Significant Accounting Policies Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Weighted Average Number of Shares Outstanding, Diluted	19,401	19,016	19,444	18,720
Earnings Per Share, Basic	$ 0.87	$ 0.44	$ 2.02	$ (0.50)
Earnings Per Share, Diluted	$ 0.85	$ 0.43	$ 1.96	$ (0.50)
Cash and Cash Equivalents, at Carrying Value	$ 164,216	$ 105,718	$ 164,216	$ 105,718	$ 207,534	$ 165,011
Net Income (Loss) Attributable to Parent	$ 16,469	$ 8,171	$ 38,100	$ (9,427)
Weighted Average Number of Shares Outstanding, Basic	18,954	18,781	18,905	18,720
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	$ 164,814	$ 106,338	$ 164,814	$ 106,338	208,162	165,569
Other Current Assets [Member]
Restricted Cash	598	265	598	265	526	139
Other Noncurrent Assets [Member]
Restricted Cash	$ 0	$ 355	$ 0	$ 355	$ 102	$ 419
Restricted Stock Units (RSUs) [Member]
Earnings Per Share, Potentially Dilutive Securities				327,000
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements	278	187	345	0
Performance Shares [Member]
Earnings Per Share, Potentially Dilutive Securities				80,000
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements	169	48	194	0

Summary of Significant Accou_11

Summary of Significant Accounting Policies Cumulative Effect Adjustments (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Jan. 01, 2018	Dec. 31, 2017
Other Assets, Current	$ 29,783	$ 26,309	$ 11,620
Assets	632,856	598,794	587,204
Deferred Tax Assets, Net of Valuation Allowance, Noncurrent	32,320	32,303	35,402
Assets, Noncurrent	249,904	240,315	243,414
Assets, Current	382,952	358,479	343,790
Deferred Revenue	42,870	30,213	31,272
Other Liabilities, Current	35,127	44,041	40,346
Liabilities, Current	272,772	268,428	265,792
Liabilities	379,023	377,135	374,499
Retained Earnings (Accumulated Deficit)	44,854	14,327	(716)
Accumulated Other Comprehensive Income (Loss), Net of Tax	4,119	7,226	13,315
Stockholders' Equity Attributable to Parent	253,833	221,659	212,705
Liabilities and Equity	$ 632,856	598,794	$ 587,204
Accounting Standards Updated 2014-09 [Domain]
Other Assets, Current		14,689
Assets		11,590
Deferred Tax Assets, Net of Valuation Allowance, Noncurrent		(3,099)
Assets, Noncurrent		(3,099)
Assets, Current		14,689
Deferred Revenue		(1,059)
Other Liabilities, Current		3,695
Liabilities, Current		2,636
Liabilities		2,636
Retained Earnings (Accumulated Deficit)		8,954
Accumulated Other Comprehensive Income (Loss), Net of Tax		0
Stockholders' Equity Attributable to Parent		8,954
Liabilities and Equity		11,590
Accounting Standards Update 2016-01 [Member]
Other Assets, Current		0
Assets		0
Deferred Tax Assets, Net of Valuation Allowance, Noncurrent		0
Assets, Noncurrent		0
Assets, Current		0
Deferred Revenue		0
Other Liabilities, Current		0
Liabilities, Current		0
Liabilities		0
Retained Earnings (Accumulated Deficit)		6,089
Accumulated Other Comprehensive Income (Loss), Net of Tax		(6,089)
Stockholders' Equity Attributable to Parent		0
Liabilities and Equity		$ 0

Summary of Significant Accou_12

Summary of Significant Accounting Policies Impact of New Accounting Pronouncements - Balance Sheet (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Jan. 01, 2018	Dec. 31, 2017
Other Assets, Current	$ 29,783	$ 26,309	$ 11,620
Assets, Current	382,952	358,479	343,790
Deferred Tax Assets, Net of Valuation Allowance, Noncurrent	32,320	32,303	35,402
Assets, Noncurrent	249,904	240,315	243,414
Assets	632,856	598,794	587,204
Employee-related Liabilities, Current	177,930		177,426
Deferred Revenue	42,870	30,213	31,272
Other Liabilities, Current	35,127	44,041	40,346
Accrued Income Taxes, Current	7,866		6,924
Liabilities, Current	272,772	268,428	265,792
Liabilities	379,023	377,135	374,499
Retained Earnings (Accumulated Deficit)	44,854	14,327	(716)
Accumulated Other Comprehensive Income (Loss), Net of Tax	4,119	7,226	13,315
Stockholders' Equity Attributable to Parent	253,833	221,659	212,705
Liabilities and Equity	632,856	$ 598,794	$ 587,204
Accounting Standards Updated 2014-09 [Domain]
Other Assets, Current	12,678
Assets, Current	365,847
Deferred Tax Assets, Net of Valuation Allowance, Noncurrent	35,419
Assets, Noncurrent	253,003
Assets	618,850
Employee-related Liabilities, Current	176,984
Deferred Revenue	43,531
Other Liabilities, Current	30,760
Accrued Income Taxes, Current	7,746
Liabilities, Current	268,000
Liabilities	374,251
Retained Earnings (Accumulated Deficit)	35,620
Stockholders' Equity Attributable to Parent	244,599
Liabilities and Equity	618,850
Accounting Standards Update 2014-09 [Member]
Other Assets, Current	17,105
Assets, Current	17,105
Deferred Tax Assets, Net of Valuation Allowance, Noncurrent	(3,099)
Assets, Noncurrent	(3,099)
Assets	14,006
Employee-related Liabilities, Current	946
Deferred Revenue	(661)
Other Liabilities, Current	4,367
Accrued Income Taxes, Current	120
Liabilities, Current	4,772
Liabilities	4,772
Retained Earnings (Accumulated Deficit)	9,234
Stockholders' Equity Attributable to Parent	9,234
Liabilities and Equity	$ 14,006

Summary of Significant Accou_13

Summary of Significant Accounting Policies Impact of New Accounting Pronouncements - Income Statement (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Sales Revenue, Services, Net	$ 187,588	$ 159,800	$ 530,718	$ 452,020
Reimbursement Revenue	4,753	4,665	13,970	13,740
Revenues	192,341	164,465	544,688	465,760
Labor and Related Expense	133,933	108,546	373,021	309,159
General And Administrative Excluding Labor And Related Expense	33,072	37,232	105,532	111,454
Cost of Reimbursable Expense	4,753	4,665	13,970	13,740
Operating Expenses	171,758	150,443	492,523	473,511
Operating Income (Loss)	20,583	14,022	52,165	(7,751)
Interest Income (Expense), Net	259	94	496	195
Other Nonoperating Income (Expense)	2,345	147	1,849	(2,773)
Nonoperating Income (Expense)	2,604	241	2,345	(2,578)
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	23,187	14,263	54,510	(10,329)
Income Tax Expense (Benefit)	6,718	6,092	16,410	(902)
Net Income (Loss) Attributable to Parent	$ 16,469	$ 8,171	$ 38,100	$ (9,427)
Earnings Per Share, Basic	$ 0.87	$ 0.44	$ 2.02	$ (0.50)
Earnings Per Share, Diluted	$ 0.85	$ 0.43	$ 1.96	$ (0.50)
Accounting Standards Update 2014-09 [Member]
Sales Revenue, Services, Net	$ 187,720		$ 529,372
Reimbursement Revenue	4,753		13,970
Revenues	192,473		543,342
Labor and Related Expense	134,017		372,075
General And Administrative Excluding Labor And Related Expense	33,072		105,532
Cost of Reimbursable Expense	4,753		13,970
Operating Expenses	171,842		491,577
Operating Income (Loss)	20,631		51,765
Interest Income (Expense), Net	259		496
Other Nonoperating Income (Expense)	2,345		1,849
Nonoperating Income (Expense)	2,604		2,345
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	23,235		54,110
Income Tax Expense (Benefit)	6,736		16,290
Net Income (Loss) Attributable to Parent	$ 16,499		$ 37,820
Earnings Per Share, Basic	$ 0.87		$ 2
Earnings Per Share, Diluted	$ 0.85		$ 1.95
Accounting Standards Update 2014-09 [Member]
Sales Revenue, Services, Net	$ (132)		$ 1,346
Reimbursement Revenue	0		0
Revenues	(132)		1,346
Labor and Related Expense	(84)		946
General And Administrative Excluding Labor And Related Expense	0		0
Cost of Reimbursable Expense	0		0
Operating Expenses	(84)		946
Operating Income (Loss)	(48)		400
Interest Income (Expense), Net	0		0
Other Nonoperating Income (Expense)	0		0
Nonoperating Income (Expense)	0		0
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	(48)		400
Income Tax Expense (Benefit)	(18)		120
Net Income (Loss) Attributable to Parent	$ (30)		$ 280
Earnings Per Share, Basic	$ 0		$ 0.02
Earnings Per Share, Diluted	$ 0		$ 0.01

Summary of Significant Accou_14

Summary of Significant Accounting Policies Impact of New Accounting Pronouncements - Cash Flow (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Net Income (Loss) Attributable to Parent	$ 16,469	$ 8,171	$ 38,100	$ (9,427)
Increase (Decrease) in Other Accrued Liabilities			3,834
Increase (Decrease) in Deferred Revenue			185	6,061
Increase (Decrease) in Income Taxes Payable, Net of Income Taxes Receivable			(2,003)	(44)
Increase (Decrease) in Other Operating Assets and Liabilities, Net			(3,761)	$ (3,000)
Accounting Standards Update 2014-09 [Member]
Net Income (Loss) Attributable to Parent	16,499		37,820
Increase (Decrease) in Other Accrued Liabilities			(1,479)
Increase (Decrease) in Deferred Revenue			2,843
Increase (Decrease) in Income Taxes Payable, Net of Income Taxes Receivable			(2,123)
Increase (Decrease) in Other Operating Assets and Liabilities, Net			(705)
Accounting Standards Update 2014-09 [Member]
Net Income (Loss) Attributable to Parent	$ (30)		280
Increase (Decrease) in Other Accrued Liabilities			5,313
Increase (Decrease) in Deferred Revenue			(2,658)
Increase (Decrease) in Income Taxes Payable, Net of Income Taxes Receivable			120
Increase (Decrease) in Other Operating Assets and Liabilities, Net			$ (3,056)

Revenue (Details)

Revenue (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Jan. 01, 2018	Dec. 31, 2017
Contract Assets and Liabilities [Line Items]
Deferred Revenue, Revenue Recognized	$ 27,400
Unbilled Contracts Receivable	7,655	$ 5,487
Increase (Decrease) in Unbilled Contracts Receivable	2,168
Contract with Customer, Asset, Net	14,334	12,398
Increase (Decrease) in Contract Assets	1,936
Deferred Revenue, Current	42,870	$ 30,370	$ 31,272
Increase (Decrease) in Contract Liabilities	12,500
Revenue Recognition, Multiple-deliverable Arrangements, Allocation to Specific Unit of Accounting, Effect of Changes, Selling Price	$ 20,900

Allowance for Doubtful Accoun_3

Allowance for Doubtful Accounts - Summary of Allowance for Doubtful Accounts (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Schedule of Allowance for Doubtful Accounts Receivable [Line Items]
Allowance for Doubtful Accounts Receivable	$ 5,131	$ 2,534
Allowance for Doubtful Accounts Receivable [Roll Forward]
Provision charged to income	3,899
Write-offs	(1,203)
Currency	$ (99)

Property and Equipment, Net - C

Property and Equipment, Net - Components of Company's Property and Equipment (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Depreciation	$ 2,700	$ 2,800	$ 8,300	$ 7,400
Property and equipment, gross	93,250		93,250		$ 94,248
Accumulated depreciation	(57,759)		(57,759)		(54,734)
Property and equipment, net	35,491		35,491		39,514
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	47,863		47,863		48,216
Office Furniture, Fixtures and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	17,960		17,960		17,732
Computer Equipment and Software [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 27,427		$ 27,427		$ 28,300

Property and Equipment, Net - A

Property and Equipment, Net - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Property, Plant and Equipment [Line Items]
Depreciation expense	$ 2.7	$ 2.8	$ 8.3	$ 7.4

Investments - Components of Com

Investments - Components of Company's Investments (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Long-term investments	$ 21,013	$ 21,319
U.S. Non-Qualified Deferred Compensation Plan [Member]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Available for sale securities	$ 21,013	$ 21,319

Investments - Additional Inform

Investments - Additional Information (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Long-term Investments	$ 21,013	$ 21,319
U.S. Non-Qualified Deferred Compensation Plan [Member]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Aggregate cost basis for investments	14,800	14,600
Fair Value, Inputs, Level 1 [Member] | U.S. Non-Qualified Deferred Compensation Plan [Member]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Long-term Investments	$ 21,000	$ 21,300

Fair Value Measurements - Level

Fair Value Measurements - Levels of Inputs Used to Measure Fair Value of Assets (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fair value of assets	$ 5,399	$ 8,810
U.S. Non-Qualified Deferred Compensation Plan [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	21,013	21,319
Assets Designated for Retirement and Pension Plans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets designated for retirement and pension plans	17,965	18,590
Pension Benefit Obligation [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Defined Benefit Plan, Benefit Obligation	(23,089)	(23,886)
Acquisition Earnout Accruals [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Acquisition earnout accruals	(10,490)	(7,213)
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fair value of assets	21,013	21,319
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | U.S. Non-Qualified Deferred Compensation Plan [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	21,013	21,319
Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fair value of assets	(5,124)	(5,296)
Significant Other Observable Inputs (Level 2) [Member] | Assets Designated for Retirement and Pension Plans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets designated for retirement and pension plans	17,965	18,590
Significant Other Observable Inputs (Level 2) [Member] | Pension Benefit Obligation [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Defined Benefit Plan, Benefit Obligation	(23,089)	(23,886)
Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fair value of assets	(10,490)	(7,213)
Significant Unobservable Inputs (Level 3) [Member] | Acquisition Earnout Accruals [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Acquisition earnout accruals	$ (10,490)	$ (7,213)

Fair Value Measurements - Recon

Fair Value Measurements - Reconciliation of Beginning and Ending Balance of Level 3 Assets and Liabilities (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2018
Fair Value, Asset and Liabilities Measured on Recurring and Nonrecurring Basis, Level 3 [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Business Combination, Acquisition Earnout Adjustment, Fair Value	$ 400
Fair Value, Inputs, Level 3 [Member] | Acquisition Earnout Accruals [Member]
Fair Value, Asset and Liabilities Measured on Recurring and Nonrecurring Basis, Level 3 [Roll Forward]
Beginning balance, acquisition earnout accruals		$ (7,213)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Business Combination, Acquisition Earnout, Fair Value		(3,054)
Earnout Accretion Fair Value Disclosure		(963)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Business Combination, Acquisition Earnout Adjustment, Fair Value		436
Foreign currency translation		304
Ending balance, acquisition earnout accruals	$ (10,490)	$ (10,490)

Acquisitions - Additional Infor

Acquisitions - Additional Information (Detail) $ in Thousands, kr in Millions	Jan. 04, 2018USD ($)	Jan. 04, 2018DKK (kr)	Sep. 30, 2018USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2017USD ($)	Dec. 31, 2017USD ($)
Business Acquisition [Line Items]
Business Combination, Consideration Transferred	$ 3,900	kr 24.3
Accretion Expense				$ 963	$ 836
Goodwill			$ 122,445	122,445		$ 118,892
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Business Combination, Acquisition Earnout Adjustment, Fair Value			$ 400
Amrop [Member] [Domain]
Business Acquisition [Line Items]
Accrued additional cash consideration	3,100
Goodwill	5,100
Finite-lived Intangible Assets Acquired				$ 1,700
Identifiable intangible assets	1,700
Goodwill acquired	$ 5,100

Goodwill and Other Intangible_5

Goodwill and Other Intangible Assets - Changes in Carrying Amount of Goodwill by Segment (Detail) - USD ($) $ in Thousands	Jan. 04, 2018	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Goodwill [Line Items]
Goodwill, Amrop Acquisition		$ 5,102
Goodwill, Gross		182,209		$ 178,656
Goodwill, Impaired, Accumulated Impairment Loss		(59,764)		(59,764)
Goodwill [Roll Forward]
Foreign currency translation		(1,549)
Goodwill, Impairment Loss			$ (29,300)
Executive Search [Member]
Goodwill [Line Items]
Goodwill, Gross		145,952		142,399
Executive Search [Member] | Americas [Member]
Goodwill [Line Items]
Goodwill, Amrop Acquisition		0
Goodwill, Gross		88,595		88,690
Goodwill, Impaired, Accumulated Impairment Loss				0
Goodwill [Roll Forward]
Foreign currency translation		(95)
Executive Search [Member] | Europe [Member]
Goodwill [Line Items]
Goodwill, Amrop Acquisition		5,102
Goodwill, Gross		48,601		44,407
Goodwill, Impaired, Accumulated Impairment Loss				(23,507)
Goodwill [Roll Forward]
Foreign currency translation		(908)
Executive Search [Member] | Asia Pacific [Member]
Goodwill [Line Items]
Goodwill, Amrop Acquisition		0
Goodwill, Gross		8,756		9,302
Goodwill, Impaired, Accumulated Impairment Loss				0
Goodwill [Roll Forward]
Foreign currency translation		(546)
Heidrick Consulting [Domain]
Goodwill [Line Items]
Goodwill, Amrop Acquisition		0
Goodwill, Gross		36,257		36,257
Goodwill, Impaired, Accumulated Impairment Loss				$ (36,257)
Goodwill [Roll Forward]
Foreign currency translation		$ 0
Amrop [Member] [Domain]
Goodwill [Line Items]
Goodwill, Acquired During Period	$ 5,100

Goodwill and Other Intangible_6

Goodwill and Other Intangible Assets - Summary of Other Intangible Assets Net by Segment (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Jan. 04, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Net Carrying Amount	$ 2,535		$ 2,158
Goodwill	122,445		118,892
Executive Search [Member]
Finite-Lived Intangible Assets [Line Items]
Net Carrying Amount	2,535		2,158
Executive Search [Member] | Americas [Member]
Finite-Lived Intangible Assets [Line Items]
Net Carrying Amount	73		252
Goodwill	88,595		88,690
Executive Search [Member] | Europe [Member]
Finite-Lived Intangible Assets [Line Items]
Net Carrying Amount	2,378		1,799
Goodwill	25,094		20,900
Executive Search [Member] | Asia Pacific [Member]
Finite-Lived Intangible Assets [Line Items]
Net Carrying Amount	84		107
Goodwill	8,756		9,302
Heidrick Consulting [Domain]
Finite-Lived Intangible Assets [Line Items]
Net Carrying Amount	0		0
Goodwill	$ 0		$ 0
Amrop [Member] [Domain]
Finite-Lived Intangible Assets [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill		$ 1,700
Goodwill		$ 5,100

Goodwill and Other Intangible_7

Goodwill and Other Intangible Assets - Carrying Amount of Amortizable Intangible Assets and Related Accumulated Amortization (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Amortization of Intangible Assets	$ 400	$ 900	$ 1,200	$ 3,900
Weighted Average Life (Years)			6 years 10 months 1 day
Gross Carrying Amount	16,718		$ 16,718		$ 14,392
Accumulated Amortization	(14,183)		(14,183)		(12,234)
Net Carrying Amount	2,535		$ 2,535		2,158
Client Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted Average Life (Years)			6 years 10 months 1 day
Gross Carrying Amount	16,053		$ 16,053		13,703
Accumulated Amortization	(13,518)		(13,518)		(11,612)
Net Carrying Amount	2,535		$ 2,535		2,091
Trade Name [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted Average Life (Years)			0 years
Gross Carrying Amount	443		$ 443		459
Accumulated Amortization	(443)		(443)		(459)
Net Carrying Amount	0		$ 0		0
Non-compete [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted Average Life (Years)			0 years
Gross Carrying Amount	222		$ 222		230
Accumulated Amortization	(222)		(222)		(163)
Net Carrying Amount	$ 0		$ 0		$ 67

Goodwill and Other Intangible_8

Goodwill and Other Intangible Assets - Intangible Assets - Additional Information (Detail) - USD ($) $ in Thousands	Jan. 04, 2018	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Amortization Expense, Remainder of Fiscal Year		$ 281		$ 281
Impairment of Intangible Assets, Finite-lived				9,900
Finite-Lived Intangible Assets, Amortization Expense, Year Two		860		860
Finite-Lived Intangible Assets, Amortization Expense, Year Three		538		538
Finite-Lived Intangible Assets, Amortization Expense, Year Four		363		363
Finite-Lived Intangible Assets, Amortization Expense, Year Five		246		246
Finite-Lived Intangible Assets, Amortization Expense, after Year Five		247		247
Intangible asset amortization expense, excluding impairment charge		400	$ 900	1,200	$ 3,900
Finite-Lived Intangible Assets, Net		$ 2,535		2,535		$ 2,158
Amrop [Member] [Domain]
Finite-Lived Intangible Assets [Line Items]
Finite-lived Intangible Assets Acquired				$ 1,700
Goodwill, Acquired During Period	$ 5,100

Goodwill and Other Intangible_9

Goodwill and Other Intangible Assets Goodwill by Segment (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Goodwill [Line Items]
Goodwill, Gross	$ 182,209	$ 178,656
Goodwill, Impaired, Accumulated Impairment Loss	(59,764)	(59,764)
Goodwill	122,445	118,892
Executive Search [Member]
Goodwill [Line Items]
Goodwill, Gross	145,952	142,399
Heidrick Consulting [Domain]
Goodwill [Line Items]
Goodwill, Gross	36,257	36,257
Goodwill, Impaired, Accumulated Impairment Loss		(36,257)
Goodwill	0	0
Americas [Member] | Executive Search [Member]
Goodwill [Line Items]
Goodwill, Gross	88,595	88,690
Goodwill, Impaired, Accumulated Impairment Loss		0
Goodwill	88,595	88,690
Europe [Member] | Executive Search [Member]
Goodwill [Line Items]
Goodwill, Gross	48,601	44,407
Goodwill, Impaired, Accumulated Impairment Loss		(23,507)
Goodwill	25,094	20,900
Asia Pacific [Member] | Executive Search [Member]
Goodwill [Line Items]
Goodwill, Gross	8,756	9,302
Goodwill, Impaired, Accumulated Impairment Loss		0
Goodwill	$ 8,756	$ 9,302

Other Non-Current Liabilities -

Other Non-Current Liabilities - Components of Other Non-Current Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Other Liabilities Disclosure [Abstract]
Premise related costs	$ 16,180	$ 18,360
Accrued earnout payments	3,373	3,076
Restructuring Reserve, Noncurrent	0	10
Other	2,216	2,151
Total other non-current liabilities	$ 21,769	$ 23,597

Other Non-Current Liabilities_3

Other Non-Current Liabilities Other Current Assets - Components of Other Current Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Other Current Assets - Components of Other Current Assets [Line Items]
Unbilled Receivables, Current	$ 21,989	$ 3,538
Other Assets, Miscellaneous, Current	$ 7,794	$ 8,082

Other Non-Current Liabilities_4

Other Non-Current Liabilities Other Current Liabilities - Components of Other Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Jan. 01, 2018	Dec. 31, 2017
Other Current Liabilities [Line Items]
Restructuring Reserve, Current	$ 2,124		$ 13,023
Other Accrued Liabilities, Current	33,003		27,323
Other Liabilities, Current	$ 35,127	$ 44,041	$ 40,346

Line of Credit - Additional Inf

Line of Credit - Additional Information (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Oct. 26, 2018	Dec. 31, 2017	Jun. 30, 2015
Line of Credit Facility [Line Items]
Proceeds from Lines of Credit	$ 20,000	$ 40,000
Long-term debt, gross	0			$ 0
Repayments of Lines of Credit	$ 20,000	$ 40,000
Senior Unsecured Revolving Line Of Credit Member [Member]
Line of Credit Facility [Line Items]
Senior unsecured revolving line of credit aggregate commitment					$ 100,000
Sublimit for letters of credit					25,000
Line of credit facility expansion feature					$ 50,000
Subsequent Event [Member]
Line of Credit Facility [Line Items]
Senior unsecured revolving line of credit aggregate commitment			$ 175,000
Sublimit for letters of credit			25,000
Line of credit facility expansion feature			$ 75,000

Stock-based Compensation - Addi

Stock-based Compensation - Additional Information (Detail) - USD ($) $ in Thousands	May 24, 2018	May 22, 2014	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Document Period End Date					Sep. 30, 2018
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense			$ 771	$ 79	$ 1,792	$ 1,561
Phantom Share Units (PSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number			114,118		114,118		0
Pre-tax unrecognized compensation expense			$ 3,300		$ 3,300
Expected time to be recognized					3 years 10 months
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period					114,118
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period					0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period					0
Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number			518,762		518,762		491,154
Pre-tax unrecognized compensation expense			$ 7,800		$ 7,800
Expected time to be recognized					2 years 11 months
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period					297,664
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period					199,550
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period					70,506
Performance Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number			197,117		197,117		185,891
Pre-tax unrecognized compensation expense			$ 3,200		$ 3,200
Expected time to be recognized					2 years
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period					102,138
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period					43,361
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period					47,551
Performance Stock Units [Member] | Executive Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance stock units vesting period					3 years
Performance Stock Units [Member] | Minimum [Member] | Executive Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance stock units, variation percentage					0.00%
Performance Stock Units [Member] | Maximum [Member] | Executive Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance stock units, variation percentage					200.00%
2012 Program [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized or reserved for issuance with respect to awards granted								1,300,000
Increase in number of shares of common stock reserved for issuance	850,000	700,000
Number of stock awards issued under 2012 Program					2,149,864
Shares available for future awards			1,368,789		1,368,789
Number of forfeited awards under 2012 Program					668,653
Labor and Related Expenses [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost			$ 2,911	199	$ 6,200	3,915
General and Administrative Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost			$ 0	$ 0	$ 563	$ 338

Stock-based Compensation - Summ

Stock-based Compensation - Summary of Information with Respect to Stock-Based Compensation (Detail) - USD ($) $ in Thousands	May 24, 2018	May 22, 2014	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
General and administrative expenses					$ 400
Income tax benefit related to stock-based compensation included in net income			$ 771	$ 79	1,792	$ 1,561
General and Administrative Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Salaries and employee benefits			$ 0	$ 0	$ 563	$ 338
Two Thousand Twelve Program [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized	850,000	700,000
Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period					2,149,864
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant			1,368,789		1,368,789
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested Options Forfeited, Number of Shares					668,653

Stock-based Compensation - Rest

Stock-based Compensation - Restricted Stock Unit Activity (Detail) - Restricted Stock Units [Member] $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2018USD ($)$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized | $	$ 7.8
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Number of stock units, beginning balance | shares	491,154
Number of stock units, granted | shares	297,664
Number of stock units, vested and converted to common stock | shares	(199,550)
Number of stock units, forfeited | shares	(70,506)
Number of stock units, ending balance | shares	518,762
Weighted-average grant-date fair value, beginning balance | $ / shares	$ 21.92
Weighted-average grant-date fair value, granted | $ / shares	34.64
Weighted-average grant-date fair value, vested and converted to common stock | $ / shares	21.66
Weighted-average grant-date fair value, forfeited | $ / shares	25.66
Weighted-average grant-date fair value, ending balance | $ / shares	$ 28.81
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	2 years 11 months

Stock-based Compensation - Perf

Stock-based Compensation - Performance Stock Unit Activity (Detail) - Performance Stock Units [Member] $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2018USD ($)$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized | $	$ 3.2
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Number of stock units, beginning balance | shares	185,891
Number of stock units, granted | shares	102,138
Number of stock units, vested and converted to common stock | shares	(43,361)
Number of stock units, forfeited | shares	(47,551)
Number of stock units, ending balance | shares	197,117
Weighted-average grant-date fair value, beginning balance | $ / shares	$ 23.82
Weighted-average grant-date fair value, granted | $ / shares	25.81
Weighted-average grant-date fair value, vested and converted to common stock | $ / shares	23.64
Weighted-average grant-date fair value, forfeited | $ / shares	24
Weighted-average grant-date fair value, ending balance | $ / shares	$ 24.88
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	2 years
Executive Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	3 years
Minimum [Member] | Executive Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage	0.00%
Maximum [Member] | Executive Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage	200.00%

Stock-based Compensation Stock-

Stock-based Compensation Stock-based Compensation - Phantom Unit Activity (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense	$ 0.4
Phantom Share Units (PSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized	$ 3.3
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	114,118	0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	114,118
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period	0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period	0
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	3 years 10 months

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Results of Operations, Income before Income Taxes [Abstract]
Income before income taxes	$ 23,187	$ 14,263	$ 54,510	$ (10,329)
Provision for income taxes	$ 6,718	$ 6,092	$ 16,410	$ (902)
Effective Income Tax Rate Reconciliation, Percent	29.00%	42.70%	30.10%	8.70%
Minimum [Member]
Results of Operations, Income before Income Taxes [Abstract]
Forecasted Annual Effective Tax Rate			31.00%
Maximum [Member]
Results of Operations, Income before Income Taxes [Abstract]
Forecasted Annual Effective Tax Rate			36.00%

Changes in Accumulated Other _3

Changes in Accumulated Other Comprehensive Income - Changes in Accumulated Other Comprehensive Income ("AOCI") by Component (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Jan. 01, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	$ 4,119		$ 4,119		$ 7,226	$ 13,315
Increase (Decrease) in Stockholders' Equity [Roll Forward]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification			8,954
Net current period other comprehensive income	(881)	$ 1,619	(3,107)	$ 7,637
Stockholders' equity attributable to parent	253,833		253,833		221,659	212,705
Available-for-Sale Securities Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	0		0			6,089
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive income before classification, net of tax			0
Amount reclassified from AOCI			0
Net current period other comprehensive income			0
Foreign Currency Translation Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	6,036		6,036			9,143
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive income before classification, net of tax			(3,107)
Amount reclassified from AOCI			0
Net current period other comprehensive income			(3,107)
Pension Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	(1,917)		(1,917)			(1,917)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive income before classification, net of tax			0
Amount reclassified from AOCI			0
Net current period other comprehensive income			0
Accumulated Other Comprehensive Income [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive income before classification, net of tax			(3,107)
Amount reclassified from AOCI			0
Net current period other comprehensive income			(3,107)
Stockholders' equity attributable to parent	$ 4,119		4,119			$ 13,315
Accounting Standards Update 2016-01 [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax					(6,089)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stockholders' equity attributable to parent					$ 0
Accounting Standards Update 2016-01 [Member] | Accumulated Other Comprehensive Income [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification			$ (6,089)

Segment Information - Revenue a

Segment Information - Revenue and Operating Income (Loss), by Segment (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Segment Reporting Information [Line Items]
Goodwill and Intangible Asset Impairment	$ 0	$ 0	$ 0	$ 39,158
Revenue
Revenue before reimbursements (net revenue)	187,588	159,800	530,718	452,020
Reimbursements	4,753	4,665	13,970	13,740
Total revenue	192,341	164,465	544,688	465,760
Operating income (loss)
Operating (loss) income	20,583	14,022	52,165	(7,751)
Operating Segments [Member]
Operating income (loss)
Operating (loss) income	28,898	21,931	79,061	19,282
Global Operations Support [Member]
Operating income (loss)
Operating (loss) income	(8,315)	(7,909)	(26,896)	(27,033)
Executive Search [Member] | Operating Segments [Member]
Revenue
Revenue before reimbursements (net revenue)	172,051	144,113	484,378	403,138
Operating income (loss)
Operating (loss) income	30,659	24,556	90,049	69,131
Heidrick Consulting [Domain] | Operating Segments [Member]
Revenue
Revenue before reimbursements (net revenue)	15,537	15,687	46,340	48,882
Operating income (loss)
Operating (loss) income	(1,761)	(2,625)	(10,988)	(49,849)
Executive Search and Leadership Consulting Americas Segment [Member] | Executive Search [Member] | Operating Segments [Member]
Revenue
Revenue before reimbursements (net revenue)	106,504	88,254	295,499	248,442
Operating income (loss)
Operating (loss) income	23,341	21,140	69,988	60,958
Executive Search and Leadership Consulting Europe Segment [Member] | Executive Search [Member] | Operating Segments [Member]
Revenue
Revenue before reimbursements (net revenue)	37,452	33,994	110,419	90,534
Operating income (loss)
Operating (loss) income	904	3,047	6,453	4,207
Executive Search and Leadership Consulting Asia Pacific Segment [Member] | Executive Search [Member] | Operating Segments [Member]
Revenue
Revenue before reimbursements (net revenue)	28,095	21,865	78,460	64,162
Operating income (loss)
Operating (loss) income	$ 6,414	$ 369	$ 13,608	$ 3,966

Guarantees - Additional Informa

Guarantees - Additional Information (Detail) $ in Millions	9 Months Ended
	Sep. 30, 2018USD ($)
Guarantees [Abstract]
Maximum undiscounted payments under outstanding guarantees	$ 2.6
Extend termination dates of the leases	extend through 2023

Subsequent Event - Additional I

Subsequent Event - Additional Information (Details) - Subsequent Event [Member] $ in Thousands	Oct. 26, 2018USD ($)
Subsequent Event [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 175,000
Sub Limit For Letters Of Credit	25,000
Swingline Loan Sublimit	10,000
Line Of Credit Facility Expansion Borrowing Capacity	$ 75,000

Restructuring (Details)

Restructuring (Details) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2018USD ($)	Dec. 31, 2017USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	$ 2,124	$ 13,025
Restructuring Charges		$ 15,700
Restructuring and Related Cost, Number of Positions Eliminated		251
Payments for Restructuring	(9,169)
Other Restructuring Costs	(1,666)
Restructuring Reserve, Foreign Currency Translation Gain (Loss)	(66)
Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	2,074	$ 11,866
Restructuring Charges		13,100
Payments for Restructuring	(7,940)
Other Restructuring Costs	(1,793)
Restructuring Reserve, Foreign Currency Translation Gain (Loss)	(59)
Other Professional and Consulting Fees [Domain]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	50	1,011
Restructuring Charges		2,300
Payments for Restructuring	(981)
Other Restructuring Costs	(27)
Restructuring Reserve, Foreign Currency Translation Gain (Loss)	(7)
Real Estate Related Expenses [Domain]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	0	148
Restructuring Charges		$ 300
Payments for Restructuring	(248)
Other Restructuring Costs	100
Restructuring Reserve, Foreign Currency Translation Gain (Loss)	$ 0