Brown & Brown (BRO) 10-K 28 Feb 18 2017 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2017	Feb. 23, 2018
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	FY
Trading Symbol	BRO
Entity Registrant Name	BROWN & BROWN, INC.
Entity Central Index Key	79,282
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		137,800,585
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float	$ 5,014,164,392

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
REVENUES
Commissions and fees	$ 1,857,270	$ 1,762,787	$ 1,656,951
Investment income	1,626	1,456	1,004
Other income, net	22,451	2,386	2,554
Total revenues	1,881,347	1,766,629	1,660,509
EXPENSES
Employee compensation and benefits	994,652	925,217	856,952
Non-cash stock-based compensation	30,631	16,052	15,513
Other operating expenses	283,470	262,872	251,055
(Gain)/loss on disposal	(2,157)	(1,291)	(619)
Amortization	85,446	86,663	87,421
Depreciation	22,698	21,003	20,890
Interest	38,316	39,481	39,248
Change in estimated acquisition earn-out payables	9,200	9,185	3,003
Total expenses	1,431,625	1,343,130	1,257,950
Income before income taxes	449,722	423,499	402,559
Income taxes	50,092	166,008	159,241
Net income	$ 399,630	$ 257,491	$ 243,318
Net income per share:
Basic (in dollars per share)	$ 2.86	$ 1.84	$ 1.72
Diluted (in dollars per share)	2.81	1.82	1.70
Dividends declared per share (in dollars per share)	$ 0.56	$ 0.50	$ 0.45

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current Assets:
Cash and cash equivalents	$ 573,383	$ 515,646
Restricted cash and investments	250,705	265,637
Short-term investments	24,965	15,048
Premiums, commissions and fees receivable	546,402	502,482
Reinsurance recoverable	477,820	78,083
Prepaid reinsurance premiums	321,017	308,661
Other current assets	47,864	50,571
Total current assets	2,242,156	1,736,128
Fixed assets, net	77,086	75,807
Goodwill	2,716,079	2,675,402
Amortizable intangible assets, net	641,005	707,454
Investments	13,949	23,048
Other assets	57,275	44,895
Total assets	5,747,550	5,262,734
Current Liabilities:
Premiums payable to insurance companies	685,163	647,564
Losses and loss adjustment reserve	476,721	78,083
Unearned premiums	321,017	308,661
Premium deposits and credits due customers	91,648	83,765
Accounts payable	64,177	69,595
Accrued expenses and other liabilities	228,748	201,989
Current portion of long-term debt	120,000	55,500
Total current liabilities	1,987,474	1,445,157
Long-term debt less unamortized discount and debt issuance costs	856,141	1,018,372
Deferred income taxes, net	256,185	357,686
Other liabilities	65,051	81,308
Shareholders’ Equity:
Common stock, par value $0.10 per share; authorized 280,000 shares; issued 148,824 shares and outstanding 138,105 shares at 2017, issued 148,107 shares and outstanding 140,104 shares at 2016	14,882	14,811
Additional paid-in capital	497,540	468,443
Treasury stock, at cost 10,719 and 8,003 shares at 2017 and 2016, respectively	(386,322)	(257,683)
Retained earnings	2,456,599	2,134,640
Total shareholders’ equity	2,582,699	2,360,211
Total liabilities and shareholders’ equity	$ 5,747,550	$ 5,262,734

CONDENSED CONSOLIDATED BALANCE4

CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Short-term Investments	$ 24,965	$ 15,048
Common stock, par value (in dollars per share)	$ 0.10	$ 0.10
Common stock, shares authorized (in shares)	280,000,000	280,000,000
Common stock, shares issued (in shares)	148,823,774	148,107,038
Common Stock, Shares, Outstanding	138,105,455	140,103,841
Treasury stock shares (in shares)	10,718,319	8,003,197
Tax effect of accumulated other comprehensive income	$ 0	$ 0

CONDENSED CONSOLIDATED STATEME5

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Cash Flows [Abstract]
Cash, Cash Equivalents and Restricted Cash	$ 824,088	$ 781,283	$ 673,173	$ 729,817
Cash flows from operating activities:
Net income	399,630	257,491	243,318
Adjustments to reconcile net income to net cash provided by operating activities:
Amortization	85,446	86,663	87,421
Depreciation	22,698	21,003	20,890
Share-based Compensation	30,631	16,052	15,513
Change in estimated acquisition earn-out payables	9,200	9,185	3,003
Deferred income taxes	(102,183)	18,163	22,696
Amortization of debt discount	158	165	157
Deferred Finance Costs, Own-share Lending Arrangement, Issuance Costs, Amortization Expense	1,682	1,597	0
Accretion (Amortization) of Discounts and Premiums, Investments	22	(39)	0
Income tax benefit from exercise of shares from the stock benefit plans	0	(7,346)	(3,276)
Payments On Acquisition Earn Outs In Excess Of Original Estimated Payables	(14,501)	(3,904)	(11,383)
Loss/(gain) on sales of investments, fixed assets and customer accounts	(1,841)	596	(107)
Changes in operating assets and liabilities, net of effect from acquisitions and divestitures:
Premiums, commissions and fees receivable (increase)	(43,306)	(63,550)	(7,163)
Reinsurance recoverables (increase)	(399,737)	(46,115)	(18,940)
Prepaid reinsurance premiums (increase) decrease	(12,356)	982	10,943
Other assets (increase)	(9,747)	(4,718)	(5,318)
Premiums payable to insurance companies decrease	37,380	66,084	542
Premium deposits and credits due customers increase (decrease)	7,750	527	(2,973)
Losses and loss adjustment reserve increase	398,638	46,115	18,940
Unearned premiums increase (decrease)	12,356	(982)	(10,943)
Accounts payable increase	26,798	30,174	34,206
Accrued expenses and other liabilities increase	25,509	8,670	8,204
Other liabilities (decrease)	(32,252)	(25,849)	(23,898)
Net cash provided by operating activities	441,975	411,042	381,832
Cash flows from investing activities:
Additions to fixed assets	(24,192)	(17,765)	(18,375)
Payments for businesses acquired, net of cash acquired	(41,471)	(122,622)	(136,000)
Proceeds from sales of fixed assets and customer accounts	4,094	4,957	10,576
Purchases of investments	(10,665)	(25,872)	(22,766)
Proceeds from Sale, Maturity and Collection of Investments	9,644	18,890	21,928
Net cash used in investing activities	(62,590)	(142,412)	(144,637)
Cash flows from financing activities:
Payments on acquisition earn-outs	(29,265)	(24,309)	(25,415)
Payments on long-term debt	(96,750)	(73,125)	(45,625)
Income tax benefit from exercise of shares from the stock benefit plans	0	7,346	3,276
Issuances of common stock for employee stock benefit plans	17,422	15,983	15,890
Repurchase of stock benefit plan shares for employees to fund tax withholdings	(7,565)	(8,495)	(2,857)
Purchase of treasury stock	(128,639)	(18,908)	(163,750)
Settlement (prepayment) of accelerated share repurchase program	(11,250)	11,250	11,250
Cash dividends paid	(77,712)	(70,262)	(64,108)
Net cash used in by financing activities	(336,580)	(160,520)	(293,839)
Payments of Debt Issuance Costs	(2,821)
Net increase (decrease) in cash and cash equivalents inclusive of restricted cash	$ 42,805	$ 108,110	$ (56,644)

Shareholders Equity Statement

Shareholders Equity Statement - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Retained Earnings [Member]
Common Stock, Shares, Outstanding		145,871
Stockholders' Equity Attributable to Parent at Dec. 31, 2014	$ 2,113,745	$ 14,587	$ 405,982	$ (75,025)	$ 1,768,201
Common Stock Issued to Directors	500,000	2,000	498,000
Dividends, Cash	$ (64,108)				(64,108)
Net Income (Loss) Attributable to Parent	243,318				243,318
Stock Issued During Period, Value, Employee Benefit Plan		528
Stock Issued During Period, Value, Employee Benefit Plan	28,045	$ 53	$ 27,992
Treasury Stock, Value, Acquired, Cost Method	(175,000)		(11,250)	(163,750)
Adjustment to Additional Paid in Capital, Income Tax Effect from Share-based Compensation, Net	3,276		3,276
Common Stock Issued to Directors Shares		16
Stockholders' Equity Attributable to Parent at Dec. 31, 2015	$ 2,149,776	$ 14,642	$ 426,498	(238,775)	1,947,411
Common Stock, Shares, Outstanding		146,415
Common Stock Issued to Directors	500,000	2,000	498,000
Dividends, Cash	$ (70,262)				(70,262)
Net Income (Loss) Attributable to Parent	257,491				257,491
Stock Issued During Period, Value, Employee Benefit Plan		1,675
Stock Issued During Period, Value, Employee Benefit Plan	23,018	$ 167	$ 22,851
Treasury Stock, Value, Acquired, Cost Method	(7,658)		11,250	(18,908)
Adjustment to Additional Paid in Capital, Income Tax Effect from Share-based Compensation, Net	7,346		7,346
Common Stock Issued to Directors Shares		17
Stockholders' Equity Attributable to Parent at Dec. 31, 2016	$ 2,360,211	$ 14,811	$ 468,443	(257,683)	2,134,640
Common Stock, Shares, Outstanding	140,103,841	148,107
Net Unrealized Holding Gain on Available for Sale Securities	$ (12)
Common Stock Issued to Directors	500,000	1,000	499,000
Dividends, Cash	$ (77,712)				(77,712)
Net Income (Loss) Attributable to Parent	399,630				399,630
Stock Issued During Period, Value, Employee Benefit Plan		706
Stock Issued During Period, Value, Employee Benefit Plan	39,965	$ 70	$ 39,895
Treasury Stock, Value, Acquired, Cost Method	(139,889)		(11,250)	(128,639)
Common Stock Issued to Directors Shares		11
Stockholders' Equity Attributable to Parent at Dec. 31, 2017	$ 2,582,699	$ 14,882	497,540	$ (386,322)	2,456,599
Common Stock, Shares, Outstanding	138,105,455	148,824
Net Unrealized Holding Gain on Available for Sale Securities	$ (6)		$ (47)		$ 41

Shareholders Equity (Parentheti

Shareholders Equity (Parenthetical) Statement - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Stockholders' Equity [Abstract]
Common Stock, Dividends, Per Share, Cash Paid	$ 0.0056	$ 0.0050	$ 0.0041

Net Income Per Share

Net Income Per Share	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Net Income Per Share	Net Income Per Share Basic EPS is computed based upon the weighted-average number of common shares (including participating securities) issued and outstanding during the period. Diluted EPS is computed based upon the weighted-average number of common shares issued and outstanding plus equivalent shares, assuming the exercise of stock options. The dilutive effect of stock options is computed by application of the treasury-stock method. The following is a reconciliation between basic and diluted weighted-average shares outstanding for the years ended December 31 : (in thousands, except per share data) 2017 2016 2015 Net income $ 399,630 $ 257,491 $ 243,318 Net income attributable to unvested awarded performance stock (9,746 ) (6,705 ) (5,695 ) Net income attributable to common shares $ 389,884 $ 250,786 $ 237,623 Weighted-average number of common shares outstanding – basic 139,697 139,779 141,113 Less unvested awarded performance stock included in weighted-average number of common shares outstanding – basic (3,407 ) (3,640 ) (3,303 ) Weighted-average number of common shares outstanding for basic earnings per common share 136,290 136,139 137,810 Dilutive effect of stock options 2,503 1,665 2,302 Weighted-average number of shares outstanding – diluted 138,793 137,804 140,112 Net income per share: Basic $ 2.86 $ 1.84 $ 1.72 Diluted $ 2.81 $ 1.82 $ 1.70

Business Combinations

Business Combinations	12 Months Ended
	Dec. 31, 2017
Business Combinations [Abstract]
Business Combinations	Business Combinations During the year ended December 31, 2017 , the Company acquired the assets and assumed certain liabilities of eleven insurance intermediaries and one book of business (customer accounts). Additionally, miscellaneous adjustments were recorded to the purchase price allocation of certain prior acquisitions completed within the last twelve months as permitted by Accounting Standards Codification Topic 805 - Business Combinations (“ASC 805”). Such adjustments are presented in the “Other” category within the following two tables. All of these businesses were acquired primarily to expand Brown & Brown’s core business and to attract and hire high-quality individuals. The recorded purchase price for all acquisitions consummated after January 1, 2009 included an estimation of the fair value of liabilities associated with any potential earn-out provisions. Subsequent changes in the fair value of earn-out obligations will be recorded in the Consolidated Statement of Income when incurred. The fair value of earn-out obligations is based upon the present value of the expected future payments to be made to the sellers of the acquired businesses in accordance with the provisions outlined in the respective purchase agreements. In determining fair value, the acquired business’s future performance is estimated using financial projections developed by management for the acquired business and reflects market participant assumptions regarding revenue growth and/or profitability. The expected future payments are estimated on the basis of the earn-out formula and performance targets specified in each purchase agreement compared to the associated financial projections. These payments are then discounted to present value using a risk-adjusted rate that takes into consideration the likelihood that the forecasted earn-out payments will be made. Based upon the acquisition date and the complexity of the underlying valuation work, certain amounts included in the Company’s Consolidated Financial Statements may be provisional and thus subject to further adjustments within the permitted measurement period, as defined in ASC 805. For the year ended December 31, 2017 , several adjustments were made within the permitted measurement period that resulted in an increase in the aggregate purchase price of the affected acquisitions of $1.5 million relating to the assumption of certain liabilities. These measurement period adjustments have been reflected as current period adjustments for the year ended December 31, 2017 in accordance with the guidance in ASU 2015-16 “Business Combinations.” The measurement period adjustments impacted goodwill, with no effect on earnings or cash in the current period. Cash paid for acquisitions was $41.5 million and $124.7 million in the years ended December 31, 2017 and 2016 , respectively. We completed eleven acquisitions (excluding book of business purchases) during the year ended December 31, 2017 . We completed eight acquisitions (excluding book of business purchases) during the year ended December 31, 2016 . The following table summarizes the purchase price allocation made as of the date of each acquisition for current year acquisitions and significant adjustments made during the measurement period for prior year acquisitions. During the measurement periods, the Company will adjust assets or liabilities if new information is obtained about facts and circumstances that existed as of the acquisition date that, if known, would have resulted in the recognition of those assets and liabilities as of that date. These adjustments are made in the period in which the amounts are determined and the current period income effect of such adjustments will be calculated as if the adjustments had been completed as of the acquisition date. (in thousands) Name Business Effective Cash Other Recorded Net Assets Maximum Other Various Various $ 41,471 $ 11,708 $ 6,921 $ 60,100 $ 27,451 Total $ 41,471 $ 11,708 $ 6,921 $ 60,100 $ 27,451 The following table summarizes the estimated fair values of the aggregate assets and liabilities acquired as of the date of each acquisition. (in thousands) Total Other current assets $ 601 Fixed assets 69 Goodwill 42,172 Purchased customer accounts 18,738 Non-compete agreements 721 Total assets acquired 62,301 Other current liabilities (1,512 ) Deferred income tax, net (689 ) Total liabilities assumed (2,201 ) Net assets acquired $ 60,100 The weighted-average useful lives for the acquired amortizable intangible assets are as follows: purchased customer accounts, 15.0 years ; and non-compete agreements, 5.0 years . Goodwill of $42.2 million was allocated to the Retail, National Programs, Wholesale Brokerage and Services Segments in the amounts of $33.1 million , $7.2 million , $1.2 million and $0.7 million , respectively. Of the total goodwill of $42.2 million , $35.3 million is currently deductible for income tax purposes. The remaining $6.9 million relates to the recorded earn-out payables and will not be deductible until it is earned and paid. For the acquisitions completed during 2017, the results of operations since the acquisition dates have been combined with those of the Company. The total revenues from the acquisitions completed through December 31, 2017 included in the Consolidated Statement of Income for the year ended December 31, 2017 were $7.8 million . The income before income taxes, including the intercompany cost of capital charge, from the acquisitions completed through December 31, 2017 included in the Consolidated Statement of Income for the year ended December 31, 2017 was $2.4 million . If the acquisitions had occurred as of the beginning of the respective periods, the Company’s results of operations would be as shown in the following table. These unaudited pro forma results are not necessarily indicative of the actual results of operations that would have occurred had the acquisitions actually been made at the beginning of the respective periods. (UNAUDITED) For the Year Ended December 31, (in thousands, except per share data) 2017 2016 Total revenues $ 1,891,701 $ 1,784,776 Income before income taxes $ 453,397 $ 429,490 Net income $ 401,908 $ 261,133 Net income per share: Basic $ 2.88 $ 1.87 Diluted $ 2.83 $ 1.85 Weighted-average number of shares outstanding: Basic 136,290 136,139 Diluted 138,793 137,804 Acquisitions in 2016 During the year ended December 31, 2016 , the Company acquired the assets and assumed certain liabilities of seven insurance intermediaries, all of the stock of one insurance intermediary and three books of business (customer accounts). Additionally, miscellaneous adjustments were recorded to the purchase price allocation of certain prior acquisitions completed within the last twelve months as permitted by ASC 805. Such adjustments are presented in the “Other” category within the following two tables. For the year ended December 31, 2016 , several adjustments were made within the permitted measurement period that resulted in a decrease in the aggregate purchase price of the affected acquisitions of $917,497 , relating to the assumption of certain liabilities. The following table summarizes the purchase price allocation made as of the date of each acquisition for current year acquisitions and significant adjustments made during the measurement period for prior year acquisitions: (in thousands) Name Business Effective Cash Note Payable Other Recorded Net Assets Maximum Social Security Advocates for the Disabled LLC (SSAD) Services February 1, 2016 $ 32,526 $ 492 $ — $ 971 $ 33,989 $ 3,500 Morstan General Agency, Inc. (Morstan) Wholesale Brokerage June 1, 2016 66,050 — 10,200 3,091 79,341 5,000 Other Various Various 26,140 — 464 400 27,004 7,785 Total $ 124,716 $ 492 $ 10,664 $ 4,462 $ 140,334 $ 16,285 The following table summarizes the estimated fair values of the aggregate assets and liabilities acquired as of the date of each acquisition. (in thousands) SSAD Morstan Other Total Cash $ 2,094 $ — $ — $ 2,094 Other current assets 1,042 2,482 1,555 5,079 Fixed assets 307 300 77 684 Goodwill 22,352 51,454 19,570 93,376 Purchased customer accounts 13,069 26,481 11,075 50,625 Non-compete agreements 72 39 117 228 Other assets — — 20 20 Total assets acquired 38,936 80,756 32,414 152,106 Other current liabilities (1,717 ) (1,415 ) (5,410 ) (8,542 ) Deferred income tax, net (3,230 ) — — (3,230 ) Total liabilities assumed (4,947 ) (1,415 ) (5,410 ) (11,772 ) Net assets acquired $ 33,989 $ 79,341 $ 27,004 $ 140,334 The weighted-average useful lives for the acquired amortizable intangible assets are as follows: purchased customer accounts, 15 years ; and non-compete agreements, 5 years . Goodwill of $93.4 million was allocated to the Retail, National Programs, Wholesale Brokerage and Services Segments in the amounts of $13.1 million , $(1.2) thousand , $57.9 million and $22.4 million , respectively. Of the total goodwill of $93.4 million , $88.9 million is currently deductible for income tax purposes. The remaining $4.5 million relates to the recorded earn-out payables and will not be deductible until it is earned and paid. For the acquisitions completed during 2016, the results of operations since the acquisition dates have been combined with those of the Company. The total revenues from the acquisitions completed through December 31, 2016 included in the Consolidated Statement of Income for the year ended December 31, 2016 were $34.2 million . The income before income taxes, including the intercompany cost of capital charge, from the acquisitions completed through December 31, 2016 included in the Consolidated Statement of Income for the year ended December 31, 2016 was $4.3 million . If the acquisitions had occurred as of the beginning of the respective periods, the Company’s results of operations would be as shown in the following table. These unaudited pro forma results are not necessarily indicative of the actual results of operations that would have occurred had the acquisitions actually been made at the beginning of the respective periods. (UNAUDITED) For the Year Ended December 31, (in thousands, except per share data) 2016 2015 Total revenues $ 1,789,790 $ 1,716,592 Income before income taxes $ 428,194 $ 414,911 Net income $ 260,346 $ 250,783 Net income per share: Basic $ 1.86 $ 1.78 Diluted $ 1.84 $ 1.75 Weighted-average number of shares outstanding: Basic 136,139 137,810 Diluted 137,804 140,112 Acquisitions in 2015 During the year ended December 31, 2015 , Brown & Brown acquired the assets and assumed certain liabilities of thirteen insurance intermediaries and four books of business (customer accounts). The cash paid for these acquisitions was $ 136.0 million . Additionally, miscellaneous adjustments were recorded to the purchase price allocation of certain prior acquisitions completed within the last twelve months as permitted by ASC 805. Such adjustments are presented in “Other” within the following two tables. All of these businesses were acquired primarily to expand Brown & Brown’s core business and to attract and hire high-quality individuals. For the year ended December 31, 2015 , several adjustments were made within the permitted measurement period that resulted in a decrease in the aggregate purchase price of the affected acquisitions of $503,442 relating to the assumption of certain liabilities. The following table summarizes the purchase price allocation made as of the date of each acquisition for current year acquisitions and significant adjustments made during the measurement period for prior year acquisitions: (in thousands) Name Business Segment Effective Date of Acquisition Cash Paid Other Payable Recorded Earn-Out Payable Net Assets Acquired Maximum Potential Earn- Out Payable Liberty Insurance Brokers, Inc. and Affiliates (Liberty) Retail February 1, 2015 $ 12,000 $ — $ 2,981 $ 14,981 $ 3,750 Spain Agency, Inc. (Spain) Retail March 1, 2015 20,706 — 2,617 23,323 9,162 Bellingham Underwriters, Inc. (Bellingham) National Programs May 1, 2015 9,007 500 3,322 12,829 4,400 Fitness Insurance, LLC (Fitness) Retail June 1, 2015 9,455 — 2,379 11,834 3,500 Strategic Benefit Advisors, Inc. (SBA) Retail June 1, 2015 49,600 400 13,587 63,587 26,000 Bentrust Financial, Inc. (Bentrust) Retail December 1, 2015 10,142 391 319 10,852 2,200 MBA Insurance Agency of Arizona, Inc. (MBA) Retail December 1, 2015 68 8,442 6,063 14,573 9,500 Smith Insurance, Inc. (Smith) Retail December 1, 2015 12,096 200 1,047 13,343 6,350 Other Various Various 12,926 95 4,584 17,605 8,212 Total $ 136,000 $ 10,028 $ 36,899 $ 182,927 $ 73,074 The following table summarizes the estimated fair values of the aggregate assets and liabilities acquired as of the date of each acquisition. The data included in the “Other” column shows a negative adjustment for purchased customer accounts. This is driven mainly by the final valuation adjustment for the acquisition of Wright. (in thousands) Liberty Spain Bellingham Fitness SBA Bentrust MBA Smith Other Total Other current assets $ 2,486 $ 324 $ — $ 9 $ 652 $ — $ — $ — $ 169 $ 3,640 Fixed assets 40 50 25 17 41 36 33 73 59 374 Goodwill 10,010 15,748 9,608 8,105 39,859 8,166 13,471 10,374 21,040 136,381 Purchased customer accounts 4,506 7,430 3,223 3,715 23,000 2,789 7,338 3,526 (2,135 ) 53,392 Non-compete agreements 24 21 21 — 21 43 11 31 156 328 Other assets — — — — 14 — — — — 14 Total assets acquired 17,066 23,573 12,877 11,846 63,587 11,034 20,853 14,004 19,289 194,129 Other current liabilities (42 ) (250 ) (48 ) (12 ) — (182 ) (6,280 ) (504 ) (4,895 ) (12,213 ) Deferred income tax, net — — — — — — — — 2,576 2,576 Other liabilities (2,043 ) — — — — — — (157 ) 635 (1,565 ) Total liabilities assumed (2,085 ) (250 ) (48 ) (12 ) — (182 ) (6,280 ) (661 ) (1,684 ) (11,202 ) Net assets acquired $ 14,981 $ 23,323 $ 12,829 $ 11,834 $ 63,587 $ 10,852 $ 14,573 $ 13,343 $ 17,605 $ 182,927 The weighted-average useful lives for the acquired amortizable intangible assets are as follows: purchased customer accounts, 15 years ; and non-compete agreements, 5 years . Goodwill of $136.4 million was allocated to the Retail, National Programs and Wholesale Brokerage Segments in the amounts of $113.8 million, $18.0 million and $4.6 million, respectively. Of the total goodwill of $136.4 million, $91.1 million is currently deductible for income tax purposes and $8.4 million is non-deductible. The remaining $36.9 million relates to the recorded earn-out payables and will not be deductible until it is earned and paid. For the acquisitions completed during 2015, the results of operations since the acquisition dates have been combined with those of the Company. The total revenues from the acquisitions completed through December 31, 2015 , included in the Consolidated Statement of Income for the year ended December 31, 2015 , were $28.2 million . The income before income taxes, including the intercompany cost of capital charge, from the acquisitions completed through December 31, 2015 , included in the Consolidated Statement of Income for the year ended December 31, 2015 , was $1.5 million. If the acquisitions had occurred as of the beginning of the respective periods, the Company’s results of operations would be as shown in the following table. These unaudited pro forma results are not necessarily indicative of the actual results of operations that would have occurred had the acquisitions actually been made at the beginning of the respective periods. (UNAUDITED) For the Year Ended December 31, (in thousands, except per share data) 2015 Total revenues $ 1,688,297 Income before income taxes $ 411,497 Net income $ 248,720 Net income per share: Basic $ 1.76 Diluted $ 1.73 Weighted-average number of shares outstanding: Basic 137,810 Diluted 140,112 As of December 31, 2017 , the maximum future contingency payments related to all acquisitions totaled $88.4 million , all of which relates to acquisitions consummated subsequent to January 1, 2009. ASC 805 is the authoritative guidance requiring an acquirer to recognize 100% of the fair values of acquired assets, including goodwill, and assumed liabilities (with only limited exceptions) upon initially obtaining control of an acquired entity. Additionally, the fair value of contingent consideration arrangements (such as earn-out purchase arrangements) at the acquisition date must be included in the purchase price consideration. As a result, the recorded purchase prices for all acquisitions consummated after January 1, 2009 include an estimation of the fair value of liabilities associated with any potential earn-out provisions. Subsequent changes in these earn-out obligations will be recorded in the Consolidated Statement of Income when incurred. Potential earn-out obligations are typically based upon future earnings of the acquired entities, usually between one and three years. As of December 31, 2017 , the fair values of the estimated acquisition earn-out payables were re-evaluated and measured at fair value on a recurring basis using unobservable inputs (Level 3) as defined in ASC 820- Fair Value Measurement . The resulting additions, payments and net changes, as well as the interest expense accretion on the estimated acquisition earn-out payables, for the years ended December 31, 2017 , 2016 and 2015 were as follows: For the Year Ended December 31, (in thousands) 2017 2016 2015 Balance as of the beginning of the period $ 63,821 $ 78,387 $ 75,283 Additions to estimated acquisition earn-out payables 6,920 4,462 36,899 Payments for estimated acquisition earn-out payables (43,766 ) (28,213 ) (36,798 ) Subtotal 26,975 54,636 75,384 Net change in earnings from estimated acquisition earn-out payables: Change in fair value on estimated acquisition earn-out payables 6,874 6,338 13 Interest expense accretion 2,326 2,847 2,990 Net change in earnings from estimated acquisition earn-out payables 9,200 9,185 3,003 Balance as of December 31, $ 36,175 $ 63,821 $ 78,387 Of the $36.2 million of estimated acquisition earn-out payables as of December 31, 2017 , $25.1 million was recorded as accounts payable, and $11.1 million was recorded as other non-current liabilities. Included within additions to estimated acquisition earn-out payables are any adjustments to opening balance sheet items prior to the one-year anniversary date of the acquisition and may therefore differ from previously reported amounts. Of the $63.8 million of estimated acquisition earn-out payables as of December 31, 2016 , $31.8 million was recorded as accounts payable, and $32.0 million was recorded as other non-current liabilities. Of the $78.4 million of estimated acquisition earn-out payables as of December 31, 2015 , $25.3 million was recorded as accounts payable, and $53.1 million

Goodwill

Goodwill	12 Months Ended
	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	Goodwill The changes in the carrying value of goodwill by reportable segment for the years ended December 31, are as follows: (in thousands) Retail National Programs Wholesale Brokerage Services Total Balance as of January 1, 2016 $ 1,345,636 $ 901,866 $ 226,961 $ 112,220 $ 2,586,683 Goodwill of acquired businesses 13,117 (1 ) 57,908 22,352 93,376 Goodwill of transferred businesses 571 (571 ) — — — Goodwill disposed of relating to sales of businesses (4,657 ) — — — (4,657 ) Balance as of December 31, 2016 $ 1,354,667 $ 901,294 $ 284,869 $ 134,572 $ 2,675,402 Goodwill of acquired businesses 33,076 7,178 1,229 689 42,172 Goodwill disposed of relating to sales of businesses (1,495 ) — — — (1,495 ) Balance as of December 31, 2017 $ 1,386,248 $ 908,472 $ 286,098 $ 135,261 $ 2,716,079

Amortizable Intangible Assets

Amortizable Intangible Assets	12 Months Ended
	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Amortizable Intangible Assets	Amortizable Intangible Assets Amortizable intangible assets at December 31, 2017 and 2016 consisted of the following: December 31, 2017 December 31, 2016 (in thousands) Gross Carrying Value Accumulated Amortization Net Carrying Value Weighted Average Life in Years (1) Gross Carrying Value Accumulated Amortization Net Carrying Value Weighted Average Life in Years (1) Purchased customer accounts $ 1,464,274 $ (824,584 ) $ 639,690 15.0 $ 1,447,680 $ (741,770 ) $ 705,910 15.0 Non-compete agreements 30,287 (28,972 ) 1,315 6.8 29,668 (28,124 ) 1,544 6.8 Total $ 1,494,561 $ (853,556 ) $ 641,005 $ 1,477,348 $ (769,894 ) $ 707,454 (1) Weighted-average life calculated as of the date of acquisition. Amortization expense for amortizable intangible assets for the years ending December 31, 2018 , 2019 , 2020 , 2021 and 2022 is estimated to be $81.0 million , $76.5 million , $69.1 million , $65.9 million and $61.4 million

Investments

Investments	12 Months Ended
	Dec. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Investments	Investments At December 31, 2017 , the Company’s amortized cost and fair values of fixed maturity securities are summarized as follows: (in thousands) Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value U.S. Treasury securities, obligations of U.S. Government agencies and Municipalities $ 29,970 $ — $ (206 ) $ 29,764 Corporate debt 1,072 12 — 1,084 Total $ 31,042 $ 12 $ (206 ) $ 30,848 At December 31, 2017 , the Company held $30.0 million in fixed income securities composed of U.S Treasury securities, securities issued by U.S. Government agencies and Municipalities, and $1.1 million issued by corporations with investment-grade ratings. Of the total, $16.9 million is classified as short-term investments on the Consolidated Balance Sheet as maturities are less than one year in duration. Additionally, the Company holds $8.1 million in short-term investments, which are related to time deposits held with various financial institutions. For securities in a loss position, the following table shows the investments’ gross unrealized loss and fair value, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position as of December 31, 2017 : (in thousands) Less than 12 Months 12 Months or More Total Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses U.S. Treasury securities, obligations of U.S. Government agencies and Municipalities $ 17,919 $ (157 ) $ 11,845 $ (49 ) $ 29,764 $ (206 ) Corporate debt 400 — — — 400 — Total $ 18,319 $ (157 ) $ 11,845 $ (49 ) $ 30,164 $ (206 ) The unrealized losses from corporate issuers were caused by interest rate increases. At December 31, 2017 , the Company had 27 securities in an unrealized loss position. The corporate securities are highly rated securities with no indicators of potential impairment. Based upon the ability and intent of the Company to hold these investments until recovery of fair value, which may be maturity, the bonds were not considered to be other-than-temporarily impaired at December 31, 2017 . At December 31, 2016 , the Company’s amortized cost and fair values of fixed maturity securities are summarized as follows: (in thousands) Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value U.S. Treasury securities, obligations of U.S. Government agencies and Municipalities $ 26,280 $ 11 $ (59 ) $ 26,232 Corporate debt 2,358 13 (1 ) 2,370 Total $ 28,638 $ 24 $ (60 ) $ 28,602 The following table shows the investments’ gross unrealized loss and fair value, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position as of December 31, 2016 : (in thousands) Less than 12 Months 12 Months or More Total Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses U.S. Treasury securities, obligations of U.S. Government agencies and Municipalities $ 14,663 $ (59 ) $ — $ — $ 14,663 $ (59 ) Corporate debt 1,001 (1 ) — — 1,001 (1 ) Total $ 15,664 $ (60 ) $ — $ — $ 15,664 $ (60 ) The unrealized losses in the Company’s investments in U.S. Treasury Securities and obligations of U.S. Government Agencies and bonds from corporate issuers were caused by interest rate increases. At December 31, 2016 , the Company had 20 securities in an unrealized loss position. The contractual cash flows of the U.S. Treasury Securities and obligations of the U.S. Government agencies investments are either guaranteed by the U.S. Government or an agency of the U.S. Government. Accordingly, it is expected that the securities would not be settled at a price less than the amortized cost of the Company’s investment. The corporate securities are highly rated securities with no indicators of potential impairment. Based upon the ability and intent of the Company to hold these investments until recovery of fair value, which may be maturity, the bonds were not considered to be other-than-temporarily impaired at December 31, 2016 . The amortized cost and estimated fair value of the fixed maturity securities at December 31, 2017 by contractual maturity are set forth below: (in thousands) Amortized Cost Fair Value Years to maturity: Due in one year or less $ 16,934 $ 16,899 Due after one year through five years 13,876 13,708 Due after five years through ten years 232 241 Total $ 31,042 $ 30,848 The amortized cost and estimated fair value of the fixed maturity securities at December 31, 2016 by contractual maturity are set forth below: (in thousands) Amortized Cost Fair Value Years to maturity: Due in one year or less $ 5,551 $ 5,554 Due after one year through five years 22,757 22,708 Due after five years through ten years 330 340 Total $ 28,638 $ 28,602 The expected maturities in the foregoing table may differ from the contractual maturities because certain borrowers have the right to call or prepay obligations with or without penalty. Proceeds from the sales and maturity of the Company’s investment in fixed maturity securities were $5.8 million . This along with maturing time deposits yielded total cash proceeds from the sale of investments of $9.6 million in the period of January 1, 2017 to December 31, 2017 . These proceeds were used to purchase additional fixed maturity securities. The gains and losses realized on those sales for the period from January 1, 2017 to December 31, 2017 were insignificant . Proceeds from the sales and maturity of the Company’s investment in fixed maturity securities were $6.0 million for the year ended December 31, 2016. This along with maturing time deposits and the utilization of funds from a money market account of $9.1 million yielded total cash proceeds from the sale of investments of $18.9 million in the period of January 1, 2016 to December 31, 2016 . These proceeds were used to purchase additional fixed- maturity securities. The gains and losses realized on those sales for the period from January 1, 2016 to December 31, 2016 were insignificant . Additionally, there was a sale of the short-duration fixed income fund which resulted in cash proceeds of $1.7 million , as the fund was liquidated in the third quarter of 2016. Gains on this sale were also insignificant . Realized gains and losses are reported on the Consolidated Statement of Income, with the cost of securities sold determined on a specific identification basis. At December 31, 2017 , investments with a fair value of approximately $4.1 million

Fixed Assets (Notes)

Fixed Assets (Notes)	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment Disclosure [Text Block]	Fixed Assets Fixed assets at December 31 consisted of the following: (in thousands) 2017 2016 Furniture, fixtures and equipment $ 190,784 $ 177,823 Leasehold improvements 35,481 33,137 Land, buildings and improvements 7,643 3,375 Total cost 233,908 214,335 Less accumulated depreciation and amortization (156,822 ) (138,528 ) Total $ 77,086 $ 75,807 Depreciation and amortization expense for fixed assets amounted to $22.7 million in 2017 , $21.0 million in 2016 and $20.9 million in 2015

Long-Term Debt

Long-Term Debt	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Long-Term Debt	Long-Term Debt Long-term debt at December 31, 2017 and 2016 consisted of the following: (in thousands) December 31, 2017 December 31, 2016 Current portion of long-term debt: Current portion of 5-year term loan facility expires 2019 $ 20,000 $ 55,000 4.500% senior notes, Series E, quarterly interest payments, balloon due 2018 100,000 — Short-term promissory note — 500 Total current portion of long-term debt 120,000 55,500 Long-term debt: Note agreements: 4.500% senior notes, Series E, quarterly interest payments, balloon due 2018 — 100,000 4.200% senior notes, semi-annual interest payments, balloon due 2024 498,943 498,785 Total notes 498,943 598,785 Credit agreements: 5-year term loan facility, periodic interest and principal payments, LIBOR plus up to 1.750%, expires June 28, 2022 365,000 426,250 5-year revolving loan facility, periodic interest payments, currently LIBOR plus up to 1.500%, plus commitment fees up to 0.250%, expires June 28, 2022 — — Total credit agreements 365,000 426,250 Debt issuance costs (contra) (7,802 ) (6,663 ) Total long-term debt less unamortized discount and debt issuance costs 856,141 1,018,372 Current portion of long-term debt 120,000 55,500 Total debt $ 976,141 $ 1,073,872 On December 22, 2006, the Company entered into a Master Shelf and Note Purchase Agreement (the “Master Agreement”) with a national insurance company (the “Purchaser”). The initial issuance of notes under the Master Agreement occurred on December 22, 2006, through the issuance of $25.0 million in Series C Senior Notes due December 22, 2016, with a fixed interest rate of 5.660% per year. On February 1, 2008, $25.0 million in Series D Senior Notes due January 15, 2015, with a fixed interest rate of 5.370% per year, were issued. On September 15, 2011, and pursuant to a Confirmation of Acceptance (the “Confirmation”), dated January 21, 2011, in connection with the Master Agreement, $100.0 million in Series E Senior Notes were issued and are due September 15, 2018, with a fixed interest rate of 4.500% per year. The Series E Senior Notes were issued for the sole purpose of retiring existing senior notes. On January 15, 2015, the Series D Notes were redeemed at maturity using cash proceeds to pay off the principal of $25.0 million plus any remaining accrued interest. On December 22, 2016, the Series C Notes were redeemed at maturity using cash proceeds to pay off the principal of $25.0 million plus any remaining accrued interest. As of December 31, 2017 , there was an outstanding debt balance issued under the provisions of the Master Agreement of $100.0 million . On April 17, 2014, the Company entered into a credit agreement with JPMorgan Chase Bank, N.A. as administrative agent and certain other banks as co-syndication agents and co-documentation agents (the “Credit Agreement”). The Credit Agreement in the amount of $1,350.0 million provides for an unsecured revolving credit facility (the “Credit Facility”) in the initial amount of $800.0 million and unsecured term loans in the initial amount of $550.0 million , either or both of which may, subject to lenders’ discretion, potentially be increased by up to $500.0 million . The Credit Facility was funded on May 20, 2014 in conjunction with the closing of the Wright acquisition, with the $550.0 million term loan being funded as well as a drawdown of $375.0 million on the revolving loan facility. Use of these proceeds was to retire existing term loan debt and to facilitate the closing of the Wright acquisition as well as other acquisitions. The Credit Facility terminates on May 20, 2019, but either or both of the revolving credit facility and the term loans may be extended for two additional one year periods at the Company’s request and at the discretion of the respective lenders. Interest and facility fees in respect to the Credit Facility are based upon the better of the Company’s net debt leverage ratio or a non-credit enhanced senior unsecured long-term debt rating. Based upon the Company’s net debt leverage ratio, the rates of interest charged on the term loan are 1.000% to 1.750% , and the revolving loan is 0.850% to 1.500% above the adjusted LIBOR rate for outstanding amounts drawn. There are fees included in the facility which include a facility fee based upon the revolving credit commitments of the lenders (whether used or unused) at a rate of 0.150% to 0.250% and letter of credit fees based upon the amounts of outstanding secured or unsecured letters of credit. The Credit Facility includes various covenants, limitations and events of default customary for similar facilities for similarly rated borrowers. On June 28, 2017, the Company entered into an amended and restated credit agreement (the “Amended and Restated Credit Agreement”) with the lenders named therein, JPMorgan Chase Bank, N.A. as administrative agent and certain other banks as co-syndication agents and co-documentation agents. The Amended and Restated Credit Agreement amended and restated the credit agreement dated April 17, 2014, among such parties (the “Original Credit Agreement”). The Amended and Restated Credit Agreement extends the applicable maturity date of the existing revolving credit facility (the “Facility”) of $800.0 million to June 28, 2022 and re-evidences unsecured term loans at $400.0 million , while also extending the applicable maturity date to June 28, 2022. The quarterly term loan principal amortization schedule was reset. At the time of the execution of the Amended and Restated Credit Agreement, $67.5 million of principal from the original unsecured term loans was repaid using operating cash balances, and the Company added an additional $2.8 million in debt issuance costs related to the Facility to the Consolidated Balance Sheet. The Company also expensed to the Consolidated Statements of Income $0.2 million of debt issuance costs related to the Original Credit Agreement due to certain lenders exiting prior to execution of the Amended and Restated Credit Agreement. The Company also carried forward $1.6 million on the Consolidated Balance Sheet the remaining unamortized portion of the Original Credit Agreement debt issuance costs, which will be amortized over the term of the Amended and Restated Credit Agreement. On December 31, 2017, the Company made a scheduled principal payment of $5.0 million per the terms of the Amended and Restated Credit Agreement. As of December 31, 2017, there was an outstanding debt balance issued under the term loan of the Amended and Restated Credit Agreement of $385.0 million with no borrowings outstanding against the Facility. Per the terms of the Amended and Restated Credit Agreement, a scheduled principal payment of $5.0 million is due March 31, 2018. On September 18, 2014, the Company issued $500.0 million of 4.200% unsecured senior notes due in 2024 . The senior notes were given investment grade ratings of BBB-/Baa3 with a stable outlook. The notes are subject to certain covenant restrictions and regulations which are customary for credit rated obligations. At the time of funding, the proceeds were offered at a discount of the original note amount which also excluded an underwriting fee discount. The net proceeds received from the issuance were used to repay the outstanding balance of $475.0 million on the revolving Credit Facility and for other general corporate purposes. As of December 31, 2017 and 2016 , there was an outstanding debt balance of $500.0 million exclusive of the associated discount balance. In conjunction with the acquisition of Social Security Advocates for the Disabled LLC (“SSAD”) effective February 1, 2016, the company agreed to a $0.5 million promissory note incurred as a payment to the sellers and payable after the one-year anniversary of the acquisition. The note had a nominal rate of interest 0.81% . On March 10, 2017, the promissory note was settled, plus any outstanding accrued interest, using cash. The Master Agreement and the Amended and Restated Credit Agreement require the Company to maintain certain financial ratios and comply with certain other covenants. The Company was in compliance with all such covenants as of December 31, 2017 and 2016 . The 30-day Adjusted LIBOR Rate as of December 31, 2017 was 1.625% . Interest paid in 2017 , 2016 and 2015 was $36.2 million , $37.7 million , and $37.5 million , respectively. At December 31, 2017 , maturities of long-term debt were $120.0 million in 2018 , $30.0 million in 2019 , $40.0 million in 2020 , $40.0 million in 2021 , $255.0 million in 2022 and $500.0 million in 2024

Income Taxes (Notes)

Income Taxes (Notes)	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income Tax Disclosure [Text Block]	Income Taxes On December 22, 2017, the U.S. government enacted the Tax Cuts and Jobs Act of 2017 (the “Tax Reform Act”). The Tax Reform Act makes broad and complex changes to the U.S. tax code that affected our income tax rate in 2017. The Tax Reform Act reduces the U.S. federal corporate income tax rate from 35.0% to 21.0% and requires companies to pay a one-time transition tax on certain unrepatriated earnings from foreign subsidiaries that is payable over eight years. The Tax Reform Act also establishes new tax laws that became effective January 1, 2018. ASC 740 requires a company to record the effects of a tax law change in the period of enactment, however, shortly after the enactment of the Tax Reform Act, the SEC staff issued SAB 118, which allows a company to record a provisional amount when it does not have the necessary information available, prepared, or analyzed in reasonable detail to complete its accounting for the change in the tax law. The measurement period ends when the company has obtained, prepared and analyzed the information necessary to finalize its accounting, but cannot extend beyond one year. We have made a reasonable estimate of the impact of the Tax Reform Act and recorded a one-time credit in our 2017 income tax expense of $120.9 million , which reflects an estimated reduction in our deferred income tax liabilities of $124.2 million as a result of the maximum federal rate decreasing to 21.0% from 35.0% , which was partially offset by an estimated increase in income tax payable in the amount of $3.3 million as a result of the transition tax on cash and cash equivalent balances related to untaxed accumulated earnings associated with our international operations. We are continuing to gather additional information related to estimates surrounding the re-measurement of our deferred tax liabilities and the transition tax on unrepatriated earnings. Significant components of the provision for income taxes for the years ended December 31 are as follows: (in thousands) 2017 2016 2015 Current: Federal $ 129,954 $ 126,145 $ 118,490 State 21,392 21,110 17,625 Foreign 929 590 430 Total current provision 152,275 147,845 136,545 Deferred: Federal 18,999 15,551 18,416 State 2,984 2,612 4,280 Foreign — — — Tax Reform Act deferred tax revaluation (124,166 ) — — Total deferred provision (102,183 ) 18,163 22,696 Total tax provision $ 50,092 $ 166,008 $ 159,241 A reconciliation of the differences between the effective tax rate and the federal statutory tax rate for the years ended December 31 is as follows: 2017 2016 2015 Federal statutory tax rate 35.0% 35.0% 35.0% State income taxes, net of federal income tax benefit 3.8 3.9 3.9 Non-deductible employee stock purchase plan expense 0.3 0.3 0.3 Non-deductible meals and entertainment 0.3 0.3 0.3 Tax Reform Act deferred tax revaluation and transition tax impact (26.9) — — Other, net (1.4) (0.3) 0.1 Effective tax rate 11.1% 39.2% 39.6% Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the corresponding amounts used for income tax reporting purposes. Significant components of Brown & Brown’s net deferred tax liabilities as of December 31 are as follows: (in thousands) 2017 2016 Non-current deferred tax liabilities: Intangible assets $ 306,351 $ 422,478 Fixed assets 2,723 6,425 Net unrealized holding (loss)/gain on available-for-sale securities (6 ) (12 ) Total non-current deferred tax liabilities 309,068 428,891 Non-current deferred tax assets: Deferred compensation 36,701 44,912 Accruals and reserves 7,534 14,032 Deferred profit-sharing contingent commissions 7,107 10,567 Net operating loss carryforwards 2,434 2,394 Valuation allowance for deferred tax assets (893 ) (700 ) Total non-current deferred tax assets 52,883 71,205 Net non-current deferred tax liability $ 256,185 $ 357,686 Income taxes paid in 2017 , 2016 and 2015 were $152.0 million , $143.1 million and $132.9 million , respectively. At December 31, 2017 , Brown & Brown had net operating loss carryforwards of $0.1 million and $52.2 million for federal and state income tax reporting purposes, respectively, portions of which expire in the years 2018 through 2037 . The federal carryforward is derived from insurance operations acquired by Brown & Brown in 2001. The state carryforward amount is derived from the operating results of certain subsidiaries and from the 2013 stock acquisition of Beecher Carlson Holdings, Inc. A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows: (in thousands) 2017 2016 2015 Unrecognized tax benefits balance at January 1 $ 750 $ 584 $ 113 Gross increases for tax positions of prior years 1,070 412 773 Gross decreases for tax positions of prior years — (41 ) — Settlements (126 ) (205 ) (302 ) Unrecognized tax benefits balance at December 31 $ 1,694 $ 750 $ 584 The Company recognizes interest and penalties related to uncertain tax positions in income tax expense. As of December 31, 2017 , 2016 and 2015 the Company had $228,608 , $86,191 and $102,171 of accrued interest and penalties related to uncertain tax positions, respectively. The total amount of unrecognized tax benefits that would affect the Company’s effective tax rate if recognized was $1.7 million as of December 31, 2017 , $750,258 as of December 31, 2016 and $583,977 as of December 31, 2015 . The Company does not expect its unrecognized tax benefits to change significantly over the next 12 months. As a result of a 2006 Internal Revenue Service (“IRS”) audit, the Company agreed to accrue at each December 31, for tax purposes only, a known amount of profit-sharing contingent commissions represented by the actual amount of profit-sharing contingent commissions received in the first quarter of the related year, with a true-up adjustment to the actual amount received by the end of the following March. Since this method for tax purposes differs from the method used for book purposes, it will result in a current deferred tax asset as of December 31 each year which will reverse by the following March 31 when the related profit-sharing contingent commissions are recognized for financial accounting purposes. The Company is subject to taxation in the United States and various state jurisdictions. The Company is also subject to taxation in the United Kingdom. In the United States, federal returns for fiscal years 2013 through 2016 remain open and subject to examination by the IRS. The Company files and remits state income taxes in various states where the Company has determined it is required to file state income taxes. The Company’s filings with those states remain open for audit for the fiscal years 2011 through 2017. In the United Kingdom, the Company’s filings remain open for audit for the fiscal years 2016 and 2017. During 2017, the Company settled the previously disclosed IRS income tax audit of The Wright Insurance Group for the short period ended May 1, 2014. Pursuant to the agreement in which the Company acquired The Wright Insurance Group, the Company was fully indemnified for all audit-related assessments. The Company and one of its subsidiaries, The Advocator Group, LLC, is currently under examination by the State of Massachusetts for the fiscal year 2013 through 2014. There are no other federal or state income tax audits as of December 31, 2017 . As a result of the Tax Reform Act, the Company has recorded a transition tax of $3.2 million . As of December 31, 2017, the Company has estimated $20.9 million

Stock Based Compensation (Notes

Stock Based Compensation (Notes)	12 Months Ended
	Dec. 31, 2017shares
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross	5,156,954
Disclosure of Compensation Related Costs, Share-based Payments [Text Block]	Stock-Based Compensation Performance Stock Plan In 1996, Brown & Brown adopted and the shareholders approved a performance stock plan, under which until the suspension of the plan in 2010, up to 14,400,000 Performance Stock Plan (“PSP”) shares could be granted to key employees contingent on the employees’ future years of service with Brown & Brown and other performance-based criteria established by the Compensation Committee of the Company’s Board of Directors. Before participants may take full title to Performance Stock, two vesting conditions must be met. Of the grants currently outstanding, specified portions satisfied the first condition for vesting based upon 20% incremental increases in the 20-trading-day average stock price of Brown & Brown’s common stock from the price on the business day prior to date of grant. Performance Stock that has satisfied the first vesting condition is considered “awarded shares.” Awarded shares are included as issued and outstanding common stock shares and are included in the calculation of basic and diluted EPS. Dividends are paid on awarded shares and participants may exercise voting privileges on such shares. Awarded shares satisfy the second condition for vesting on the earlier of a participant’s: (i) 15 years of continuous employment with Brown & Brown from the date shares are granted to the participants (or, in the case of the July 2009 grant to Powell Brown , 20 years ), (ii) attainment of age 64 (on a prorated basis corresponding to the number of years since the date of grant), or (iii) death or disability. On April 28, 2010, the PSP was suspended and any remaining authorized, but unissued shares, as well as any shares forfeited in the future, will be reserved for issuance under the 2010 Stock Incentive Plan (the “SIP”). At December 31, 2017 , 5,156,954 shares had been granted under the PSP. As of December 31, 2017 , 847,238 shares had met the first condition of vesting and had been awarded, and 4,309,716 shares had satisfied both conditions of vesting and had been distributed to participants. Of the shares that have not vested as of December 31, 2017 , the initial stock prices ranged from $15.58 to $25.68 . The Company uses a path-dependent lattice model to estimate the fair value of PSP grants on the grant date. A summary of PSP activity for the years ended December 31, 2017 , 2016 and 2015 is as follows: Weighted- Average Grant Date Fair Value Granted Shares Awarded Shares Shares Not Yet Awarded Outstanding at January 1, 2015 $ 8.71 1,928,631 1,903,213 25,418 Granted $ — — — — Awarded $ — — — — Vested $ 5.55 (208,889 ) (208,889 ) — Forfeited $ 9.78 (117,528 ) (100,110 ) (17,418 ) Outstanding at December 31, 2015 $ 9.03 1,602,214 1,594,214 8,000 Granted $ — — — — Awarded $ — — 4,000 (4,000 ) Vested $ 6.39 (506,422 ) (506,422 ) — Forfeited $ 10.52 (92,517 ) (88,517 ) (4,000 ) Outstanding at December 31, 2016 $ 10.23 1,003,275 1,003,275 — Granted $ — — — — Awarded $ — — — — Vested $ 9.61 (138,801 ) (138,801 ) — Forfeited $ 10.47 (17,236 ) (17,236 ) — Outstanding at December 31, 2017 $ 10.32 847,238 847,238 — The total fair value of PSP grants that vested during each of the years ended December 31, 2017 , 2016 and 2015 was $6.3 million , $18.1 million and $6.8 million , respectively. Stock Incentive Plan On April 28, 2010 , the shareholders of Brown & Brown, Inc. approved the Stock Incentive Plan (“SIP”) that provides for the granting of stock options, stock, restricted stock units, and/or stock appreciation rights to employees and directors contingent on criteria established by the Compensation Committee of the Company’s Board of Directors. The principal purpose of the SIP is to attract, incentivize and retain key employees by offering those persons an opportunity to acquire or increase a direct proprietary interest in the Company’s operations and future success. The SIP includes a sub-plan applicable to Decus Insurance Brokers Limited (“Decus”) which, is a subsidiary of Decus Holdings (U.K.) Limited. The shares of stock reserved for issuance under the SIP are any shares that are authorized for issuance under the PSP and not already subject to grants under the PSP, and that were outstanding as of April 28, 2010 , the date of suspension of the PSP, together with PSP shares and SIP shares forfeited after that date. As of April 28, 2010 , 6,046,768 shares were available for issuance under the PSP, which were then transferred to the SIP. In addition, in May 2016 and May 2017 our shareholders approved an amendment to the SIP to increase the shares available for issuance by an additional 1,200,000 and 1,300,000, respectively. The Company has granted stock grants to our employees in the form of Restricted Stock Awards and Performance Stock Awards under the SIP. To date, a substantial majority of stock grants to employees under the SIP vest in four to ten years The Performance Stock Awards are subject to the achievement of certain performance criteria by grantees, which may include growth in a defined book of business, organic growth and operating profit growth of a profit center, EBITDA growth, organic growth of the Company and consolidated EPS growth at certain levels of the Company. The performance measurement period ranges from three to five years. Beginning in 2016, certain Performance Stock Awards have a payout range between 0% to 200% depending on the achievement against the stated performance target. Prior to 2016, the majority of the grants had a binary performance measurement criteria that only allowed for 0% or 100% payout. Non-employee members of the Board of Directors received shares annually issued pursuant to the SIP as part of their annual compensation. A total of 15,700 shares were issued in January 2015 , 16,860 shares were issued in January 2016 and 11,350 shares were issued in January 2017 . The following table sets forth information as of December 31, 2017 , 2016 and 2015 , with respect to the number of time-based restricted shares granted and awarded, the number of performance-based restricted shares granted, and the number of performance-based restricted shares awarded under our Performance Stock Plan and 2010 Stock Incentive Plan: Year Time-Based Restricted Stock Granted and Awarded Performance-Based Restricted Stock Granted Performance-Based Restricted Stock Awarded 2017 120,667 575,789 (1) 163,404 2016 182,653 789,446 (2) 1,435,319 2015 164,646 316,520 — (1) Of the 575,789 shares of performance-based restricted stock granted in 2017 , the payout for 320,826 shares may be increased up to 200% of the target or decreased to zero, subject to the level of performance attained. The amount reflected in the table includes all restricted stock grants at a target payout of 100% . (2) Of the 789,446 shares of performance-based restricted stock granted in 2016 , the payout for 353,132 shares may be increased up to 200% of the target or decreased to zero, subject to the level of performance attained. The amount reflected in the table includes all restricted stock grants at a target payout of 100% . At December 31, 2017 , 4,197,920 shares were available for future grants. This amount is calculated assuming the maximum payout for all restricted stock grants. The Company uses the closing stock price on the day prior to the grant date to determine the fair value of SIP grants and then applies an estimated forfeiture factor to estimate the annual expense. Additionally, the Company uses the path-dependent lattice model to estimate the fair value of grants with PSP-type vesting conditions as of the grant date. SIP shares that satisfied the first vesting condition for PSP-type grants or the established performance criteria are considered awarded shares. Awarded shares are included as issued and outstanding common stock shares and are included in the calculation of basic and diluted EPS. A summary of SIP activity for the years ended December 31, 2017 , 2016 and 2015 is as follows: Weighted- Average Grant Date Fair Value Granted Shares Awarded Shares Shares Not Yet Awarded Outstanding at January 1, 2015 $ 28.19 6,659,047 1,060,890 5,598,157 Granted $ 31.74 481,166 164,646 316,520 Awarded $ — — — — Vested $ — — — — Forfeited $ 26.32 (863,241 ) (95,542 ) (767,699 ) Outstanding at December 31, 2015 $ 28.74 6,276,972 1,129,994 5,146,978 Granted $ 35.52 972,099 182,653 789,446 (1) Awarded $ 24.93 — 1,431,319 (1,431,319 ) Vested $ 27.31 (166,884 ) (166,884 ) — Forfeited $ 25.34 (954,131 ) (175,788 ) (778,343 ) Outstanding at December 31, 2016 $ 29.96 6,128,056 2,401,294 3,726,762 Granted $ 41.65 696,456 120,667 575,789 (2) Awarded $ 31.44 — 163,404 (163,404 ) Vested $ 25.22 (242,457 ) (242,457 ) — Forfeited $ 29.77 (171,060 ) (38,106 ) (132,954 ) Outstanding at December 31, 2017 $ 31.16 6,410,995 2,404,802 4,006,193 (1) Of the 789,446 shares of performance-based restricted stock granted in 2016, the payout for 353,132 shares may be increased up to 200% of the target or decreased to zero, subject to the level of performance attained. The amount reflected in the table includes all restricted stock grants at a target payout of 100% . (2) Of the 575,789 shares of performance-based restricted stock granted in 2016, the payout for 320,826 shares may be increased up to 200% of the target or decreased to zero, subject to the level of performance attained. The amount reflected in the table includes all restricted stock grants at a target payout of 100% . Employee Stock Purchase Plan The Company has a shareholder-approved Employee Stock Purchase Plan (“ESPP”) with a total of 17,000,000 authorized shares of which 4,151,251 were available for future subscriptions as of December 31, 2017 . Employees of the Company who regularly work 20 hours or more per week are eligible to participate in the ESPP. Participants, through payroll deductions, may allot up to 10% of their compensation towards the purchase of a maximum of $25,000 worth of Company stock between August 1st of each year and the following July 31st (the “Subscription Period”) at a cost of 85% of the lower of the stock price as of the beginning or end of the Subscription Period. The Company estimates the fair value of an ESPP share option as of the beginning of the Subscription Period as the sum of: (1) 15% of the quoted market price of the Company’s stock on the day prior to the beginning of the Subscription Period, and (2) 85% of the value of a one-year stock option on the Company stock using the Black-Scholes option-pricing model. The estimated fair value of an ESPP share option as of the Subscription Period beginning in August 2017 was $8.64 . The fair values of an ESPP share option as of the Subscription Periods beginning in August 2016 and 2015 , were $7.61 and $6.43 , respectively. For the ESPP plan years ended July 31, 2017 , 2016 and 2015 , the Company issued 529,012 , 514,665 and 539,389 shares of common stock, respectively. These shares were issued at an aggregate purchase price of $16.4 million , or $31.03 per share, in 2017 , $15.0 million , or $29.23 per share, in 2016 , and $14.4 million , or $26.62 per share, in 2015 . For the five months ended December 31, 2017 , 2016 and 2015 (portions of the 2017-2018, 2016-2017 and 2015-2016 plan years), 217,514 , 247,023 and 231,803 shares of common stock (from authorized but unissued shares), respectively, were subscribed to by ESPP participants for proceeds of approximately $8.2 million , $7.7 million and $6.8 million , respectively. Incentive Stock Option Plan On April 21, 2000 , Brown & Brown adopted, and the shareholders approved, a qualified incentive stock option plan (the “ISOP”) that provides for the granting of stock options to certain key employees for up to 4,800,000 shares of common stock. On December 31, 2008 , the ISOP expired. The objective of the ISOP was to provide additional performance incentives to grow Brown & Brown’s pre-tax income in excess of 15% annually. The options were granted at the most recent trading day’s closing market price and vest over a period of 1 -to- 10 years , with a potential acceleration of the vesting period to 3 -to- 6 years based upon achievement of certain performance goals. All of the options expire 10 years after the grant date. The Company uses the Black-Scholes option-pricing model to estimate the fair value of stock options on the grant date. The risk-free interest rate is based upon the U.S. Treasury yield curve on the date of grant with a remaining term approximating the expected term of the option granted. The expected term of the options granted is derived from historical data; grantees are divided into two groups based upon expected exercise behavior and are considered separately for valuation purposes. The expected volatility is based upon the historical volatility of the Company’s common stock over the period of time equivalent to the expected term of the options granted. The dividend yield is based upon the Company’s best estimate of future dividend yield. A summary of stock option activity for the years ended December 31, 2017 , 2016 and 2015 is as follows: Stock Options Shares Under Option Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term (in years) Aggregate Intrinsic Value (in thousands) Outstanding at January 1, 2015 470,356 $ 18.57 3.1 $ 5,087 Granted — $ — Exercised (151,767 ) $ 18.48 Forfeited (49,000 ) $ 19.36 Expired — $ — Outstanding at December 31, 2015 269,589 $ 18.48 2.2 $ 2,395 Granted — $ — Exercised (64,589 ) $ 18.48 Forfeited (30,000 ) $ 18.48 Expired — $ — Outstanding at December 31, 2016 175,000 $ 18.48 1.2 $ 4,616 Granted — $ — Exercised (175,000 ) $ 18.48 Forfeited — $ — Expired — $ — Outstanding at December 31, 2017 — $ — N/A $ — Ending vested and expected to vest at December 31, — $ — N/A $ — Exercisable at December 31, 2017 — $ — N/A $ — Exercisable at December 31, 2016 175,000 $ 18.48 1.2 $ 4,616 Exercisable at December 31, 2015 164,589 $ 18.48 2.2 $ 2,241 The total intrinsic value of options exercised, determined as of the date of exercise, during the years ended December 31, 2017 , 2016 and 2015 was $4.7 million , $1.0 million and $2.2 million , respectively. The total intrinsic value is calculated as the difference between the exercise price of all underlying awards and the quoted market price of the Company’s stock for all in-the-money stock options at December 31, 2017 , 2016 and 2015 , respectively. There are no option shares available for future grant under the ISOP since this plan expired as of December 31, 2008 . Summary of Non-Cash Stock-Based Compensation Expense The non-cash stock-based compensation expense for the years ended December 31 is as follows: (in thousands) 2017 2016 2015 Stock Incentive Plan $ 24,899 $ 11,049 $ 11,111 Employee Stock Purchase Plan 4,025 3,698 3,430 Performance Stock Plan 1,707 1,305 972 Incentive Stock Option Plan — — — Total $ 30,631 $ 16,052 $ 15,513 Summary of Unamortized Compensation Expense As of December 31, 2017 , there was approximately $87.9 million of unamortized compensation expense related to all non-vested stock-based compensation arrangements granted under the Company’s stock-based compensation plans. That expense is expected to be recognized over a weighted-average period of 3.62

Supplemental Disclosures of Cas

Supplemental Disclosures of Cash Flow Information and Non-Cash Financing and Investing Activities	12 Months Ended
	Dec. 31, 2017
Supplemental Cash Flow Elements [Abstract]
Supplemental Disclosures of Cash Flow Information and Non-Cash Financing and Investing Activities	The following is a reconciliation of cash and cash equivalents inclusive of restricted cash as of December 31, 2017 , 2016 and 2015 . Balance as of December 31, (in thousands) 2017 2016 2015 Table to reconcile cash and cash equivalents inclusive of restricted cash Cash and cash equivalents $ 573,383 $ 515,646 443,420 Restricted cash 250,705 265,637 229,753 Total cash and cash equivalents inclusive of restricted cash at the end of the period $ 824,088 $ 781,283 673,173

Quarterly Operating Results (No

Quarterly Operating Results (Notes)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Information [Text Block]	Quarterly Operating Results (Unaudited) Quarterly operating results for 2017 and 2016 were as follows: (in thousands, except per share data) First Quarter Second Quarter Third Quarter Fourth Quarter 2017 Total revenues $ 465,080 $ 466,305 $ 475,646 $ 474,316 Total expenses $ 354,113 $ 358,303 $ 351,227 $ 367,982 Income before income taxes $ 110,967 $ 108,002 $ 124,419 $ 106,334 Net income $ 70,110 $ 66,102 $ 75,913 $ 187,505 Net income per share: Basic $ 0.50 $ 0.47 $ 0.54 $ 1.35 Diluted $ 0.49 $ 0.46 $ 0.53 $ 1.32 (1) 2016 Total revenues $ 424,173 $ 446,518 $ 462,274 $ 433,664 Total expenses $ 321,624 $ 337,441 $ 345,302 $ 338,763 Income before income taxes $ 102,549 $ 109,077 $ 116,972 $ 94,901 Net income $ 62,070 $ 66,250 $ 71,545 $ 57,626 Net income per share: Basic $ 0.45 $ 0.47 $ 0.51 $ 0.41 Diluted $ 0.44 $ 0.47 $ 0.50 $ 0.41 (1) Includes $0.85 impact associated with recording impact of Tax Reform Act.

Segment Information

Segment Information	12 Months Ended
	Dec. 31, 2017
Segment Reporting [Abstract]
Segment Information	Segment Information Brown & Brown’s business is divided into four reportable segments: (1) the Retail Segment, which provides a broad range of insurance products and services to commercial, public and quasi-public entities, and to professional and individual customers, (2) the National Programs Segment, which acts as a MGA, provides professional liability and related package products for certain professionals, a range of insurance products for individuals, flood coverage, and targeted products and services designated for specific industries, trade groups, governmental entities and market niches, all of which are delivered through nationwide networks of independent agents, and Brown & Brown retail agents, (3) the Wholesale Brokerage Segment, which markets and sells excess and surplus commercial and personal lines insurance, primarily through independent agents and brokers, as well as Brown & Brown retail agents, and (4) the Services Segment, which provides insurance-related services, including third-party claims administration and comprehensive medical utilization management services in both the workers’ compensation and all-lines liability arenas, as well as Medicare Set-aside services, Social Security disability and Medicare benefits advocacy services and claims adjusting services. Brown & Brown conducts all of its operations within the United States of America, except for a Wholesale Brokerage operation based in London, England, and Retail operations in Bermuda and the Cayman Islands. These operations earned $15.9 million , $14.5 million and $13.4 million of total revenues for the years ended December 31, 2017 , 2016 and 2015 , respectively. Long-lived assets held outside of the United States during each of these three years were not material. Additionally, we have a licenses to operate as a broker in various Canadian provinces. The accounting policies of the reportable segments are the same as those described in Note 1. The Company evaluates the performance of its segments based upon revenues and income before income taxes. Inter-segment revenues are eliminated. Summarized financial information concerning the Company’s reportable segments is shown in the following table. The “Other” column includes any income and expenses not allocated to reportable segments and corporate-related items, including the intercompany interest expense charge to the reporting segment. For the year ended December 31, 2017 (in thousands) Retail National Programs Wholesale Brokerage Services Other Total Total revenues $ 943,460 $ 479,813 $ 271,737 $ 165,372 $ 20,965 $ 1,881,347 Investment income $ 8 $ 384 $ — $ 299 $ 935 $ 1,626 Amortization $ 42,164 $ 27,277 $ 11,456 $ 4,548 $ 1 $ 85,446 Depreciation $ 5,210 $ 6,325 $ 1,885 $ 1,600 $ 7,678 $ 22,698 Interest expense $ 31,133 $ 35,561 $ 6,263 $ 3,522 $ (38,163 ) $ 38,316 Income before income taxes $ 196,616 $ 109,961 $ 68,844 $ 30,498 $ 43,803 $ 449,722 Total assets $ 4,255,515 $ 3,267,486 $ 1,260,239 $ 399,240 $ (3,434,930 ) $ 5,747,550 Capital expenditures $ 4,494 $ 5,936 $ 1,836 $ 1,033 $ 10,893 $ 24,192 For the year ended December 31, 2016 (in thousands) Retail National Programs Wholesale Brokerage Services Other Total Total revenues $ 917,406 $ 448,516 $ 243,103 $ 156,365 $ 1,239 $ 1,766,629 Investment income $ 37 $ 628 $ 4 $ 283 $ 504 $ 1,456 Amortization $ 43,447 $ 27,920 $ 10,801 $ 4,485 $ 10 $ 86,663 Depreciation $ 6,191 $ 7,868 $ 1,975 $ 1,881 $ 3,088 $ 21,003 Interest expense $ 38,216 $ 45,738 $ 3,976 $ 4,950 $ (53,399 ) $ 39,481 Income before income taxes $ 188,001 $ 91,762 $ 62,623 $ 24,338 $ 56,775 $ 423,499 Total assets (1) $ 3,854,393 $ 2,711,378 $ 1,108,829 $ 371,645 $ (2,783,511 ) $ 5,262,734 Capital expenditures $ 5,951 $ 6,977 $ 1,301 $ 656 $ 2,880 $ 17,765 For the year ended December 31, 2015 (in thousands) Retail National Programs Wholesale Brokerage Services Other Total Total revenues $ 870,346 $ 428,734 $ 216,996 $ 145,365 $ (932 ) $ 1,660,509 Investment income $ 87 $ 210 $ 150 $ 42 $ 515 $ 1,004 Amortization $ 45,145 $ 28,479 $ 9,739 $ 4,019 $ 39 $ 87,421 Depreciation $ 6,558 $ 7,250 $ 2,142 $ 1,988 $ 2,952 $ 20,890 Interest expense $ 41,036 $ 55,705 $ 891 $ 5,970 $ (64,354 ) $ 39,248 Income before income taxes $ 181,938 $ 67,673 $ 64,708 $ 19,713 $ 68,527 $ 402,559 Total assets (1) $ 3,507,476 $ 2,503,537 $ 895,782 $ 285,459 $ (2,212,410 ) $ 4,979,844 Capital expenditures $ 6,797 $ 6,001 $ 3,084 $ 1,088 $ 1,405 $ 18,375 (1)

Losses and Loss Adjustment Rese

Losses and Loss Adjustment Reserve	12 Months Ended
	Dec. 31, 2017
Reinsurance Disclosures [Abstract]
Losses and Loss Adjustment Reserve	Although the reinsurers are liable to the Company for amounts reinsured, our subsidiary, WNFIC remains primarily liable to its policyholders for the full amount of the policies written whether or not the reinsurers meet their obligations to the Company when they become due. The effects of reinsurance on premiums written and earned at December 31 are as follows: 2017 2016 (in thousands) Written Earned Written Earned Direct premiums $ 604,623 $ 592,267 $ 591,142 $ 592,123 Assumed premiums — — — — Ceded premiums 604,610 592,254 591,124 592,105 Net premiums $ 13 $ 13 $ 18 $ 18 All premiums written by WNFIC under the National Flood Insurance Program are 100% ceded to FEMA, for which WNFIC received a 30.9% expense allowance from January 1, 2017 through December 31, 2017. As of December 31, 2017 and 2016 , the Company ceded $602.9 million and $589.5 million of written premiums, respectively. Effective April 1, 2014, WNFIC is also a party to a quota share agreement whereby it cedes 100% of its gross excess flood premiums, excluding fees, to Arch Reinsurance Company and receives a 30.5% commission. WNFIC ceded $1.7 million and $1.6 million for the years ended December 31, 2017 and 2016 . As of December 31, 2017 , WNFIC had $1.1 million in paid excess flood losses, $16,606 in loss adjustment expenses, case reserves of $838,307 and incurred but not reported of $1.5 million . WNFIC also ceded 100% , of the Homeowners, Private Passenger Auto Liability, and Other Liability Occurrence to Stillwater Insurance Company, formerly known as Fidelity National Insurance Company. This business is in runoff. Therefore, only loss data still exists on this business. As of December 31, 2017 , no ceded unpaid losses and loss adjustment expenses or incurred but not reported balance for Homeowners, Private Passenger Auto Liability and Other Liability Occurrence. As of December 31, 2017 , the Consolidated Balance Sheet contained Reinsurance recoverable of $477.8 million and Prepaid reinsurance premiums of $321.0 million . As of December 31, 2016 , the Consolidated Balance Sheet contained reinsurance recoverable of $78.1 million and prepaid reinsurance premiums of $308.7 million . There was $1.1 million net activity in the reserve for losses and loss adjustment expense for the year ended December 31, 2017 , and no net activity in the reserve for losses and loss adjustment expense for the year ended December 31, 2016 , as WNFIC’s direct premiums written were 100% ceded to two reinsurers. The balance of the reserve for losses and loss adjustment expense, excluding related reinsurance recoverables was $477.8 million as of December 31, 2017 and $78.1 million as of December 31, 2016

Statutory Financial Information

Statutory Financial Information	12 Months Ended
	Dec. 31, 2017
Statutory Accounting Practices [Abstract]
Statutory Financial Information	Statutory Financial Information WNFIC maintains capital in excess of minimum statutory amount of $7.5 million as required by regulatory authorities. The statutory capital and surplus of WNFIC was $28.7 million as of December 31, 2017 and $23.5 million as of December 31, 2016 . As of December 31, 2017 and 2016 , WNFIC generated statutory net income of $4.8 million and $8.2 million

Subsidiary Dividend Restriction

Subsidiary Dividend Restrictions	12 Months Ended
	Dec. 31, 2017
Disclosure of Restrictions on Dividends, Loans and Advances Disclosure [Abstract]
Subsidiary Dividend Restrictions	Subsidiary Dividend Restrictions Under the insurance regulations of Texas, where WNFIC in incorporated, the maximum amount of ordinary dividends that WNFIC can pay to shareholders in a rolling twelve month period is limited to the greater of 10% of statutory adjusted capital and surplus as shown on WNFIC’s last annual statement on file with the superintendent of the Texas Department of Insurance or 100% of adjusted net income. There was no dividend payout in 2017 and the maximum dividend payout that may be made in 2018 without prior approval is $4.8 million

Shareholders' Equity

Shareholders' Equity	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
Shareholders' Equity	Shareholders’ Equity On July 18, 2014, the Company’s Board of Directors authorized the repurchase of up to $200.0 million of its shares of common stock, and on July 20, 2015, the Company’s Board of Directors authorized the repurchase of up to an additional $400.0 million of the Company’s outstanding common stock. Under the authorization from the Company’s Board of Directors, shares may be purchased from time to time, at the Company’s discretion and subject to the availability of stock, market conditions, the trading price of the stock, alternative uses for capital, the Company’s financial performance and other potential factors. These purchases may be carried out through open market purchases, block trades, accelerated share repurchase plans of up to $100.0 million each (unless otherwise approved by the Board of Directors), negotiated private transactions or pursuant to any trading plan that may be adopted in accordance with Rule 10b5-1 of the Securities Exchange Act of 1934. Between May 18, 2017 and July 14, 2017, the Company made share repurchases in the open market in total of 348,460 shares at a total cost of $14.9 million . On August 14, 2017, the Company entered into accelerated share repurchase agreement ("ASR") with an investment bank to purchase an aggregate $50.0 million of the Company's common stock. As part of the ASR, the company received an initial delivery of 967,888 shares of the Company's common stock with a fair market value of approximately $42.5 million . Upon maturity of the program, the Company received 108,288 shares, relieving the remaining balance of $7.5 million at settlement on October 16, 2017 for a total delivery of 1,076,176 shares of the Company's common stock. On November 14, 2017, the Company entered into an ASR with an investment bank to purchase an aggregate $75.0 million of the Company's common stock. As part of the ASR, the company received an initial delivery of 1,290,486 shares of the Company's common stock with a fair market value of approximately $63.8 million . Upon maturity of the program, the Company received 168,227 shares, relieving the remaining balance of $11.2 million at settlement on February 9, 2018 for a total delivery of 1,458,713 shares of the Company's common stock. During 2014, the Company repurchased 2,384,760 shares at an average price per share of $31.46 for a total cost of $75.0 million under the original share repurchase authorization from the Board of Directors on July 18, 2014. During 2015, the Company repurchased 5,408,819 shares at an average price per share of $32.35 for a total cost of $175.0 million under the current share repurchase authorization, while exhausting the previous authorization of $200.0 million from the Board of Directors in 2014. During 2016, the Company repurchased 209,618 shares at an average price per share of $36.53 for a total cost of $7.7 million under the current share repurchase authorization. At December 31, 2017, the remaining amount authorized by our Board of Directors for share repurchases was $238.7 million . Under the authorized repurchase programs, the Company has repurchased a total of approximately 10.7 million shares for an aggregate cost of approximately $386.3 million

Legal and Regulatory Proceeding

Legal and Regulatory Proceedings	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Legal and Regulatory Proceedings	Operating Leases Brown & Brown leases facilities and certain items of office equipment under non-cancelable operating lease arrangements expiring on various dates through 2042. The facility leases generally contain renewal options and escalation clauses based upon increases in the lessors’ operating expenses and other charges. Brown & Brown anticipates that most of these leases will be renewed or replaced upon expiration. At December 31, 2017 , the aggregate future minimum lease payments under all non-cancelable lease agreements were as follows: (in thousands) 2018 $ 42,970 2019 39,005 2020 34,236 2021 27,715 2022 21,996 Thereafter 44,496 Total minimum future lease payments $ 210,418 Rental expense in 2017 , 2016 and 2015 for operating leases totaled $51.0 million , $49.3 million and $46.0 million , respectively. Legal Proceedings The Company records losses for claims in excess of the limits of, or outside the coverage of, applicable insurance at the time and to the extent they are probable and estimable. In accordance with ASC Topic 450- Contingencies , the Company accrues anticipated costs of settlement, damages, losses for liability claims and, under certain conditions, costs of defense, based upon historical experience or to the extent specific losses are probable and estimable. Otherwise, the Company expenses these costs as incurred. If the best estimate of a probable loss is a range rather than a specific amount, the Company accrues the amount at the lower end of the range. The Company’s accruals for legal matters that were probable and estimable were not material at December 31, 2017 and 2016 . We continue to assess certain litigation and claims to determine the amounts, if any, that management believes will be paid as a result of such claims and litigation and, therefore, additional losses may be accrued and paid in the future, which could adversely impact the Company’s operating results, cash flows and overall liquidity. The Company maintains third-party insurance policies to provide coverage for certain legal claims, in an effort to mitigate its overall exposure to unanticipated claims or adverse decisions. However, as (i) one or more of the Company’s insurance carriers could take the position that portions of these claims are not covered by the Company’s insurance, (ii) to the extent that payments are made to resolve claims and lawsuits, applicable insurance policy limits are eroded and (iii) the claims and lawsuits relating to these matters are continuing to develop, it is possible that future results of operations or cash flows for any particular quarterly or annual period could be materially affected by unfavorable resolutions of these matters. Based upon the AM Best Company ratings of these third-party insurers, management does not believe there is a substantial risk of an insurer’s material non-performance related to any current insured claims.

Summary of Significant Accounti

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Average Annual Operating Profit Earned Period Maximum	3 years
Fair Value of Financial Instruments, Policy [Policy Text Block]	Fair Value of Financial Instruments The carrying amounts of Brown & Brown’s financial assets and liabilities, including cash and cash equivalents; restricted cash and short-term investments; investments; premiums, commissions and fees receivable; reinsurance recoverable; prepaid reinsurance premiums; premiums payable to insurance companies; losses and loss adjustment reserve; unearned premium; premium deposits and credits due customers and accounts payable, at December 31, 2017 and 2016 , approximate fair value because of the short-term maturity of these instruments. The carrying amount of Brown & Brown’s long-term debt approximates fair value at December 31, 2017 and 2016 as our fixed-rate borrowings of $598.9 million approximate their values using market quotes of notes with the similar terms as ours, which we deem a close approximation of current market rates. Of the $598.9 million , $100.0 million is related to short-term notes which approximates the carrying value due to the proximity to maturity. The estimated fair value of the $385.0 million
Nature of Operations	Summary of Significant Accounting Policies Nature of Operations Brown & Brown, Inc., a Florida corporation, and its subsidiaries (collectively, “Brown & Brown” or the “Company”) is a diversified insurance agency, wholesale brokerage, insurance programs and services organization that markets and sells to its customers, insurance products and services, primarily in the property, casualty and employee benefits areas. Brown & Brown’s business is divided into four reportable segments: the Retail Segment provides a broad range of insurance products and services to commercial, public and quasi-public entities, professional and individual customers; the National Programs Segment, acting as a managing general agent (“MGA”), provides professional liability and related package products for certain professionals, a range of insurance products for individuals, flood coverage, and targeted products and services designated for specific industries, trade groups, governmental entities and market niches, all of which are delivered through nationwide networks of independent agents, including Brown & Brown retail agents; the Wholesale Brokerage Segment markets and sells excess and surplus commercial insurance, primarily through independent agents and brokers, as well as Brown & Brown Retail offices; and the Services Segment provides insurance-related services, including third-party claims administration and comprehensive medical utilization management services in both the workers’ compensation and all-lines liability arenas, as well as Medicare Set-aside services, Social Security disability and Medicare benefits advocacy services, and claims adjusting services. Recently Issued Accounting Pronouncements In November 2016, the Financial Accountings Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2016-18, “Statement of Cash Flows (Topic 230)”: Restricted Cash (“ASU 2016-18”), which requires that the Statement of Cash Flows explain the changes during the period of cash and cash equivalents inclusive of amounts categorized as restricted cash. ASU 2016-18 is effective for periods beginning after December 15, 2017. However, the Company elected to early adopt for the reporting period beginning January 1, 2017 under the full retrospective approach for all periods presented. With the adoption of ASU 2016-18, the change in restricted cash is no longer reflected as a change in operating assets and liabilities, and the Statement of Cash Flows details the changes in the balance of cash and cash equivalents inclusive of restricted cash. Net cash provided by operating activities for the years ended December 31, 2015 and 2016 were previously reported as $411.8 million and $375.2 million , respectively. With the retrospective adoption, the net cash provided by operating activities for the years ended December 31, 2015 and 2016 is now reported as $381.8 million and $411.0 million , respectively. The Company reflects cash collected from customers that is payable to insurance companies as restricted cash if segregation of this cash is required by the state of domicile for the office conducting this transaction or if required by contract with the relevant insurance company providing coverage. Cash collected from customers that is payable to insurance companies is reported in cash and cash equivalents if no such restriction is required. In August 2016, the FASB issued ASU 2016-15, “Statement of Cash Flows (Topic 230)”: Classification of Certain Cash Receipts and Cash Payments (a consensus of the Emerging Issues Task Force) (“ASU 2016-15”), which addresses eight specific cash flow issues with the objective of reducing the existing diversity in practice in how certain cash receipts and cash payments are presented and classified and applies to all entities, including both business entities and not-for-profit entities that are required to present a statement of cash flows under Topic 230. ASU 2016-15 will take effect for public companies for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017 and early adoption is permitted. The Company is adopting this change effective January 1, 2018 and has evaluated the impact of ASU 2016-15 determining that there is no impact on the Company’s Statement of Cash Flows. The Company already presents cash paid on contingent consideration in business combination as prescribed by ASU 2016-15 and does not, at this time, engage in the other activities being addressed. In March 2016, the FASB issued ASU 2016-09, “Improvements to Employee Share Based Payment Accounting” (“ASU 2016-09”), which amends guidance issued in Accounting Standards Codification (“ASC”) Topic 718, Compensation - Stock Compensation. ASU 2016-09 simplifies several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. ASU 2016-09 is effective for fiscal years beginning after December 15, 2016, and interim periods within those fiscal years and early adoption is permitted. The Company adopted the guidance on January 1, 2017, as required. Prior periods have not been adjusted, as the guidance was adopted prospectively. The principal impact is that the tax benefit or expense from stock compensation is now presented in the income tax line of the Statement of Income, whereas the prior treatment was to present this amount as a component of equity on the Balance Sheet. In addition, the tax benefit or expense is now presented as activity in Cash Flow from Operating Activity, rather than the prior presentation as Cash Flow from Financing Activity in the Statement of Cash Flows. The Company also continues to estimate forfeitures of stock grants as allowed by ASU 2016-09. In March 2016, the FASB issued ASU 2016-08, “Principal Versus Agent Considerations (Reporting Revenue Gross Versus Net)” (“ASU 2016-08”) to clarify certain aspects of the principal-versus-agent guidance included in the new revenue standard ASU 2014-09 “Revenue from Contracts with Customers” (“ASU 2014-09”). The FASB issued the ASU in response to concerns identified by stakeholders, including those related to (1) determining the appropriate unit of account under the revenue standard’s principal-versus-agent guidance and (2) applying the indicators of whether an entity is a principal or an agent in accordance with the revenue standard’s control principle. ASU 2016-08 is effective contemporaneous with ASU 2014-09 beginning January 1, 2018. The impact of adopting ASU 2016-08 is not material to the Company. In February 2016, the FASB issued ASU 2016-02, “Leases (Topic 842)” (“ASU 2016-02”), which provides guidance for accounting for leases. Under ASU 2016-02, the Company will be required to recognize the assets and liabilities for the rights and obligations created by leased assets. ASU 2016-02 will take effect for public companies for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. The Company continues to evaluate the impact of this pronouncement with the principal impact being that the present value of the remaining lease payments be presented as a liability on the Balance Sheet as well as an asset of similar value representing the “Right of Use” for those leased properties. As detailed in Note 13 of the 2016 10-K, the undiscounted contractual cash payments remaining on leased properties was $213.2 million as of December 31, 2016 and is $210.4 million as of December 31, 2017 as detailed in “Management’s Discussion and Analysis of Financial Condition and Results of Operations - Liquidity and Capital Resources” and Note 13 “Commitments and Contingencies.” In November 2015, FASB issued ASU No. 2015-17, “Income Taxes (Topic 740) - Balance Sheet Classification of Deferred Taxes” (“ASU 2015-17”), which simplifies the presentation of deferred income taxes by requiring deferred tax assets and liabilities be classified as a single non-current item on the balance sheet. ASU 2015-17 is effective for fiscal years beginning after December 15, 2016 with early adoption permitted as of the beginning of any interim or annual reporting period. The Company adopted the guidance on January 1, 2017, as required. As a result, the Company retrospectively applied the guidance to the 2016 balance sheet by reclassifying $24.6 million from deferred income taxes (asset) to deferred income taxes, net (liability) on the Condensed Consolidated Balance Sheet. This reclassification occurred prior to the passage of the Tax Cuts and Jobs Act of 2017, which had a material impact on the value of deferred tax items. See Note 9 “Income Taxes” for more information. In May 2014, FASB issued ASU No. 2014-09, “Revenue from Contracts with Customers (Topic 606)” (“Topic 606”), which provides guidance for revenue recognition. Topic 606 affects any entity that either enters into contracts with customers to transfer goods or services or enters into contracts for the transfer of non-financial assets. It supersedes the revenue recognition requirements in Topic 605, “Revenue Recognition,” and most industry-specific guidance. The standard’s core principle is that a company should recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which a company expects to be entitled in exchange for those goods or services. In doing so, companies will need to use more judgment and make more estimates than under the current guidance. Specifically, in situations where multiple performance obligations exist within a contract, the use of estimates is required to allocate the transaction price to each separate performance obligation. Historically, approximately 70% of the Company’s commissions and fees are in the form of commissions paid by insurance carriers. These commissions are earned upon the effective date of bound coverage, as no significant performance obligation remains after coverage is bound. The following areas are impacted by the adoption of Topic 606: Installment billing - Prior to the adoption of Topic 606, commission revenues related to installment billings were recognized on the latter of the policy effective date (as indicated in the policy) or the date that the premium was billed to the client (as indicated on the premium invoice), with the exception of our Arrowhead businesses, which follow a policy of recognizing these revenues on the latter of the policy effective date or processed date into our systems, regardless of the billing arrangement. As a result of the adoption of Topic 606, revenue associated with the issuance of policies will be recognized upon the effective date of the associated policy, which means that commission revenues billed on an installment basis will be now recognized earlier than they had been previously resulting in revenue will accrued based upon the completion of the performance obligation and thus creating a current asset for the unbilled revenue until such time as an invoice is generated, typically not to exceed twelve months. The Company does not expect the overall impact of these changes to be significant on a full-year basis, but the timing of recognizing revenue will be impacted among quarters when compared to prior years. Contingent commissions - Prior to the adoption of Topic 606, revenue that was not fixed and determinable because a contingency exists was not recognized until the contingency was resolved. Under Topic 606, the Company must use its judgment to estimate the amount of consideration that will be received such that a significant reversal of revenue is not probable. Contingent commissions represent a form of variable consideration associated with the same performance obligation, which is the placement of coverage, for which we earn core commissions. In connection with the new standard, contingent commissions will be estimated with an appropriate constraint applied and accrued relative to the recognition of the corresponding core commissions. The resulting effect on the timing of recognition of contingent commissions will more closely follow a similar pattern as our core commissions with true-ups recognized when payments are received or as additional information that affects the estimate becomes available. Contingent commissions have averaged approximately 3.6% of the previous year’s total commissions and fees over the last three years and have primarily been received in the first and second quarters of the year. Approximately 30% of the Company’s commissions and fees is in the form of fees, which are predominantly in our National Programs and Services Segments, and to a lesser extent in the large accounts business within our Retail Segment, where we receive fees in lieu of a commission. In accordance with Topic 606, fee revenue from certain agreements will be recognized in earlier periods and others in later periods as compared to our current accounting treatment. The Company does not expect the overall impact of these changes to be significant on a full-year basis, but the timing of recognizing revenue will be impacted among quarters when compared to prior years. Additionally, the Company has evaluated ASC Topic 340 - Other Assets and Deferred Cost (“ASC 340”) which requires companies to defer certain incremental costs to obtain customer contracts, and certain costs to fulfill customer contracts. Incremental cost to obtain - the adoption of ASC 340 will result in the Company deferring certain cost to obtain customer contracts primarily as they relate to commission based compensation plans in the Retail Segment, in which the Company pays an incremental amount of compensation on new business in the first year of the contract. These incremental costs will be deferred and amortized over a 15-year period, which is consistent with the analysis performed on acquired customer accounts and referenced in Note 4 to the Company’s financial statements. Cost to fulfill - the adoption of ASC 340 will result in the Company deferring certain costs to fulfill a contract and recognize these costs as the associated performance obligations are fulfilled. In order for contract fulfillment costs to be deferred under ASC 340, the costs must (1) relate directly to a specific contract or anticipated contract, (2) generate or enhance resources that the Company will use in satisfying its obligations under the contract, and (3) be expected to be recovered through sufficient net cash flows from the contract. The Company does not expect the overall impact of these changes to be significant on a full-year basis, but the timing of recognizing these expenses will be impacted among quarters to better align with the associated revenue. Topic 606 is effective for the Company beginning January 1, 2018. Entities are permitted to adopt the guidance under one of the following methods: the “full retrospective” method, which applies the guidance to each period presented (prior years restated), or the “modified retrospective” method, in which the guidance is only applied to the year of adoption, with the cumulative effect of initially applying the guidance recognized as an adjustment to retained earnings. The Company has elected to follow the modified retrospective method applied to contracts that are not completed as of the date of adoption. The estimated cumulative impact of adopting the standard on January 1, 2018 is an increase in stockholders’ equity of between $70.0 million and $110.0 million . In connection with the implementation of this standard, we expect to modify, and in some instances institute additional accounting procedures, processes and internal controls. Given the relative expected impacts of this standard to our revenue streams, we do not expect that these modifications and additions will materially change our internal controls over financial reporting. Principles of Consolidation The accompanying Consolidated Financial Statements include the accounts of Brown & Brown, Inc. and its subsidiaries. All significant intercompany account balances and transactions have been eliminated in the Consolidated Financial Statements. Segment results for prior periods have been recast, where appropriate, to reflect the current year segmental structure. Certain reclassifications have been made to the prior year amounts reported in this Annual Report on Form 10-K in order to conform to the current year presentation. Revenue Recognition Commission revenues are recognized as of the effective date of the insurance policy or the date on which the policy premium is processed into our systems and invoiced to the customer, whichever is later. Commission revenues related to installment billings are recognized on the latter of effective or invoiced date, with the exception of our Arrowhead business which follows a policy of recognizing on the latter of effective or processed date into our systems, regardless of the billing arrangement. Management determines the policy cancellation reserve based upon historical cancellation experience adjusted for any known circumstances. Subsequent commission adjustments were recognized upon our receipt of notification from insurance companies concerning matters necessitating such adjustments. Profit-sharing contingent commissions are recognized when determinable, which is generally when such commissions are received from insurance companies, or when we receive formal notification of the amount of such payments. Fee revenues and commissions for workers’ compensation programs are recognized as services are rendered. Use of Estimates The preparation of the Consolidated Financial Statements in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, as well as disclosures of contingent assets and liabilities, at the date of the Consolidated Financial Statements, and the reported amounts of revenues and expenses during the reporting period. Actual results may differ from those estimates. Cash and Cash Equivalents Cash and cash equivalents principally consist of demand deposits with financial institutions and highly liquid investments with quoted market prices having maturities of three months or less when purchased. Restricted Cash and Investments, and Premiums, Commissions and Fees Receivable In our capacity as an insurance agent or broker, the Company typically collects premiums from insureds and, after deducting the authorized commissions, remits the net premiums to the appropriate insurance company or companies. Accordingly, as reported in the Consolidated Balance Sheets, “premiums” are receivable from insureds. Unremitted net insurance premiums are held in a fiduciary capacity until Brown & Brown disburses them. Where allowed by law, Brown & Brown invests these unremitted funds only in cash, money market accounts, tax-free variable-rate demand bonds and commercial paper held for a short term. In certain states in which Brown & Brown operates, the use and investment alternatives for these funds are regulated and restricted by various state laws and agencies. These restricted funds are reported as restricted cash and investments on the Consolidated Balance Sheets. The interest income earned on these unremitted funds, where allowed by state law, is reported as investment income in the Consolidated Statement of Income. In other circumstances, the insurance companies collect the premiums directly from the insureds and remit the applicable commissions to Brown & Brown. Accordingly, as reported in the Consolidated Balance Sheets, “commissions” are receivables from insurance companies. “Fees” are primarily receivables due from customers. Investments Certificates of deposit, and other securities, having maturities of more than three months when purchased are reported at cost and are adjusted for other-than-temporary market value declines. The Company’s investment holdings include U.S. Government securities, municipal bonds, domestic corporate and foreign corporate bonds as well as short-duration fixed income funds. Investments within the portfolio or funds are held as available for sale and are carried at their fair value. Any gain/loss applicable from the fair value change is recorded, net of tax, as other comprehensive income within the equity section of the Consolidated Balance Sheet. Realized gains and losses are reported on the Consolidated Statement of Income, with the cost of securities sold determined on a specific identification basis. Fixed Assets Fixed assets, including leasehold improvements, are carried at cost, less accumulated depreciation and amortization. Expenditures for improvements are capitalized, and expenditures for maintenance and repairs are expensed to operations as incurred. Upon sale or retirement, the cost and related accumulated depreciation and amortization are removed from the accounts and the resulting gain or loss, if any, is reflected in other income. Depreciation has been determined using the straight-line method over the estimated useful lives of the related assets, which range from 3 to 15 years. Leasehold improvements are amortized on the straight-line method over the shorter of the useful life of the improvement or the term of the related lease. Goodwill and Amortizable Intangible Assets All of our business combinations initiated after June 30, 2001 are accounted for using the acquisition method. Acquisition purchase prices are typically based upon a multiple of average annual operating profit earned over a period of 3 years within a minimum and maximum price range. The recorded purchase prices for all acquisitions consummated after January 1, 2009 include an estimation of the fair value of liabilities associated with any potential earn-out provisions. Subsequent changes in the fair value of earn-out obligations are recorded in the Consolidated Statement of Income when incurred. The fair value of earn-out obligations is based upon the present value of the expected future payments to be made to the sellers of the acquired businesses in accordance with the provisions contained in the respective purchase agreements. In determining fair value, the acquired business’ future performance is estimated using financial projections developed by management for the acquired business and this estimate reflects market participant assumptions regarding revenue growth and/or profitability. The expected future payments are estimated on the basis of the earn-out formula and performance targets specified in each purchase agreement compared to the associated financial projections. These estimates are then discounted to present value using a risk-adjusted rate that takes into consideration the likelihood that the forecasted earn-out payments will be made. Amortizable intangible assets are stated at cost, less accumulated amortization, and consist of purchased customer accounts and non-compete agreements. Purchased customer accounts and non-compete agreements are amortized on a straight-line basis over the related estimated lives and contract periods, which range from 3 to 15 years. Purchased customer accounts primarily consist of records and files that contain information about insurance policies and the related insured parties that are essential to policy renewals. The excess of the purchase price of an acquisition over the fair value of the identifiable tangible and amortizable intangible assets is assigned to goodwill. While goodwill is not amortizable, it is subject to assessment at least annually, and more frequently in the presence of certain circumstances, for impairment by application of a fair value-based test. The Company compares the fair value of each reporting unit with its carrying amount to determine if there is potential impairment of goodwill. If the fair value of the reporting unit is less than its carrying value, an impairment loss is recorded to the extent that the fair value of the goodwill within the reporting unit is less than its carrying value. Fair value is estimated based upon multiples of earnings before interest, income taxes, depreciation, amortization and change in estimated acquisition earn-out payables (“EBITDAC”), or on a discounted cash flow basis. Brown & Brown completed its most recent annual assessment as of November 30, 2017 and determined that the fair value of goodwill significantly exceeded the carrying value of such assets. In addition, as of December 31, 2017, there are no accumulated impairment losses. The carrying value of amortizable intangible assets attributable to each business or asset group comprising Brown & Brown is periodically reviewed by management to determine if there are events or changes in circumstances that would indicate that its carrying amount may not be recoverable. Accordingly, if there are any such changes in circumstances during the year, Brown & Brown assesses the carrying value of its amortizable intangible assets by considering the estimated future undiscounted cash flows generated by the corresponding business or asset group. Any impairment identified through this assessment may require that the carrying value of related amortizable intangible assets be adjusted. There were no impairments recorded for the years ended December 31, 2017, 2016 and 2015. Income Taxes Brown & Brown records income tax expense using the asset-and-liability method of accounting for deferred income taxes. Under this method, deferred tax assets and liabilities are recognized for the expected future tax consequences of temporary differences between the financial statement carrying values and the income tax bases of Brown & Brown’s assets and liabilities.
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements In November 2016, the Financial Accountings Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2016-18, “Statement of Cash Flows (Topic 230)”: Restricted Cash (“ASU 2016-18”), which requires that the Statement of Cash Flows explain the changes during the period of cash and cash equivalents inclusive of amounts categorized as restricted cash. ASU 2016-18 is effective for periods beginning after December 15, 2017. However, the Company elected to early adopt for the reporting period beginning January 1, 2017 under the full retrospective approach for all periods presented. With the adoption of ASU 2016-18, the change in restricted cash is no longer reflected as a change in operating assets and liabilities, and the Statement of Cash Flows details the changes in the balance of cash and cash equivalents inclusive of restricted cash. Net cash provided by operating activities for the years ended December 31, 2015 and 2016 were previously reported as $411.8 million and $375.2 million , respectively. With the retrospective adoption, the net cash provided by operating activities for the years ended December 31, 2015 and 2016 is now reported as $381.8 million and $411.0 million , respectively. The Company reflects cash collected from customers that is payable to insurance companies as restricted cash if segregation of this cash is required by the state of domicile for the office conducting this transaction or if required by contract with the relevant insurance company providing coverage. Cash collected from customers that is payable to insurance companies is reported in cash and cash equivalents if no such restriction is required. In August 2016, the FASB issued ASU 2016-15, “Statement of Cash Flows (Topic 230)”: Classification of Certain Cash Receipts and Cash Payments (a consensus of the Emerging Issues Task Force) (“ASU 2016-15”), which addresses eight specific cash flow issues with the objective of reducing the existing diversity in practice in how certain cash receipts and cash payments are presented and classified and applies to all entities, including both business entities and not-for-profit entities that are required to present a statement of cash flows under Topic 230. ASU 2016-15 will take effect for public companies for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017 and early adoption is permitted. The Company is adopting this change effective January 1, 2018 and has evaluated the impact of ASU 2016-15 determining that there is no impact on the Company’s Statement of Cash Flows. The Company already presents cash paid on contingent consideration in business combination as prescribed by ASU 2016-15 and does not, at this time, engage in the other activities being addressed. In March 2016, the FASB issued ASU 2016-09, “Improvements to Employee Share Based Payment Accounting” (“ASU 2016-09”), which amends guidance issued in Accounting Standards Codification (“ASC”) Topic 718, Compensation - Stock Compensation. ASU 2016-09 simplifies several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. ASU 2016-09 is effective for fiscal years beginning after December 15, 2016, and interim periods within those fiscal years and early adoption is permitted. The Company adopted the guidance on January 1, 2017, as required. Prior periods have not been adjusted, as the guidance was adopted prospectively. The principal impact is that the tax benefit or expense from stock compensation is now presented in the income tax line of the Statement of Income, whereas the prior treatment was to present this amount as a component of equity on the Balance Sheet. In addition, the tax benefit or expense is now presented as activity in Cash Flow from Operating Activity, rather than the prior presentation as Cash Flow from Financing Activity in the Statement of Cash Flows. The Company also continues to estimate forfeitures of stock grants as allowed by ASU 2016-09. In March 2016, the FASB issued ASU 2016-08, “Principal Versus Agent Considerations (Reporting Revenue Gross Versus Net)” (“ASU 2016-08”) to clarify certain aspects of the principal-versus-agent guidance included in the new revenue standard ASU 2014-09 “Revenue from Contracts with Customers” (“ASU 2014-09”). The FASB issued the ASU in response to concerns identified by stakeholders, including those related to (1) determining the appropriate unit of account under the revenue standard’s principal-versus-agent guidance and (2) applying the indicators of whether an entity is a principal or an agent in accordance with the revenue standard’s control principle. ASU 2016-08 is effective contemporaneous with ASU 2014-09 beginning January 1, 2018. The impact of adopting ASU 2016-08 is not material to the Company. In February 2016, the FASB issued ASU 2016-02, “Leases (Topic 842)” (“ASU 2016-02”), which provides guidance for accounting for leases. Under ASU 2016-02, the Company will be required to recognize the assets and liabilities for the rights and obligations created by leased assets. ASU 2016-02 will take effect for public companies for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. The Company continues to evaluate the impact of this pronouncement with the principal impact being that the present value of the remaining lease payments be presented as a liability on the Balance Sheet as well as an asset of similar value representing the “Right of Use” for those leased properties. As detailed in Note 13 of the 2016 10-K, the undiscounted contractual cash payments remaining on leased properties was $213.2 million as of December 31, 2016 and is $210.4 million as of December 31, 2017 as detailed in “Management’s Discussion and Analysis of Financial Condition and Results of Operations - Liquidity and Capital Resources” and Note 13 “Commitments and Contingencies.” In November 2015, FASB issued ASU No. 2015-17, “Income Taxes (Topic 740) - Balance Sheet Classification of Deferred Taxes” (“ASU 2015-17”), which simplifies the presentation of deferred income taxes by requiring deferred tax assets and liabilities be classified as a single non-current item on the balance sheet. ASU 2015-17 is effective for fiscal years beginning after December 15, 2016 with early adoption permitted as of the beginning of any interim or annual reporting period. The Company adopted the guidance on January 1, 2017, as required. As a result, the Company retrospectively applied the guidance to the 2016 balance sheet by reclassifying $24.6 million from deferred income taxes (asset) to deferred income taxes, net (liability) on the Condensed Consolidated Balance Sheet. This reclassification occurred prior to the passage of the Tax Cuts and Jobs Act of 2017, which had a material impact on the value of deferred tax items. See Note 9 “Income Taxes” for more information. In May 2014, FASB issued ASU No. 2014-09, “Revenue from Contracts with Customers (Topic 606)” (“Topic 606”), which provides guidance for revenue recognition. Topic 606 affects any entity that either enters into contracts with customers to transfer goods or services or enters into contracts for the transfer of non-financial assets. It supersedes the revenue recognition requirements in Topic 605, “Revenue Recognition,” and most industry-specific guidance. The standard’s core principle is that a company should recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which a company expects to be entitled in exchange for those goods or services. In doing so, companies will need to use more judgment and make more estimates than under the current guidance. Specifically, in situations where multiple performance obligations exist within a contract, the use of estimates is required to allocate the transaction price to each separate performance obligation. Historically, approximately 70% of the Company’s commissions and fees are in the form of commissions paid by insurance carriers. These commissions are earned upon the effective date of bound coverage, as no significant performance obligation remains after coverage is bound. The following areas are impacted by the adoption of Topic 606: Installment billing - Prior to the adoption of Topic 606, commission revenues related to installment billings were recognized on the latter of the policy effective date (as indicated in the policy) or the date that the premium was billed to the client (as indicated on the premium invoice), with the exception of our Arrowhead businesses, which follow a policy of recognizing these revenues on the latter of the policy effective date or processed date into our systems, regardless of the billing arrangement. As a result of the adoption of Topic 606, revenue associated with the issuance of policies will be recognized upon the effective date of the associated policy, which means that commission revenues billed on an installment basis will be now recognized earlier than they had been previously resulting in revenue will accrued based upon the completion of the performance obligation and thus creating a current asset for the unbilled revenue until such time as an invoice is generated, typically not to exceed twelve months. The Company does not expect the overall impact of these changes to be significant on a full-year basis, but the timing of recognizing revenue will be impacted among quarters when compared to prior years. Contingent commissions - Prior to the adoption of Topic 606, revenue that was not fixed and determinable because a contingency exists was not recognized until the contingency was resolved. Under Topic 606, the Company must use its judgment to estimate the amount of consideration that will be received such that a significant reversal of revenue is not probable. Contingent commissions represent a form of variable consideration associated with the same performance obligation, which is the placement of coverage, for which we earn core commissions. In connection with the new standard, contingent commissions will be estimated with an appropriate constraint applied and accrued relative to the recognition of the corresponding core commissions. The resulting effect on the timing of recognition of contingent commissions will more closely follow a similar pattern as our core commissions with true-ups recognized when payments are received or as additional information that affects the estimate becomes available. Contingent commissions have averaged approximately 3.6% of the previous year’s total commissions and fees over the last three years and have primarily been received in the first and second quarters of the year. Approximately 30% of the Company’s commissions and fees is in the form of fees, which are predominantly in our National Programs and Services Segments, and to a lesser extent in the large accounts business within our Retail Segment, where we receive fees in lieu of a commission. In accordance with Topic 606, fee revenue from certain agreements will be recognized in earlier periods and others in later periods as compared to our current accounting treatment. The Company does not expect the overall impact of these changes to be significant on a full-year basis, but the timing of recognizing revenue will be impacted among quarters when compared to prior years. Additionally, the Company has evaluated ASC Topic 340 - Other Assets and Deferred Cost (“ASC 340”) which requires companies to defer certain incremental costs to obtain customer contracts, and certain costs to fulfill customer contracts. Incremental cost to obtain - the adoption of ASC 340 will result in the Company deferring certain cost to obtain customer contracts primarily as they relate to commission based compensation plans in the Retail Segment, in which the Company pays an incremental amount of compensation on new business in the first year of the contract. These incremental costs will be deferred and amortized over a 15-year period, which is consistent with the analysis performed on acquired customer accounts and referenced in Note 4 to the Company’s financial statements. Cost to fulfill - the adoption of ASC 340 will result in the Company deferring certain costs to fulfill a contract and recognize these costs as the associated performance obligations are fulfilled. In order for contract fulfillment costs to be deferred under ASC 340, the costs must (1) relate directly to a specific contract or anticipated contract, (2) generate or enhance resources that the Company will use in satisfying its obligations under the contract, and (3) be expected to be recovered through sufficient net cash flows from the contract. The Company does not expect the overall impact of these changes to be significant on a full-year basis, but the timing of recognizing these expenses will be impacted among quarters to better align with the associated revenue. Topic 606 is effective for the Company beginning January 1, 2018. Entities are permitted to adopt the guidance under one of the following methods: the “full retrospective” method, which applies the guidance to each period presented (prior years restated), or the “modified retrospective” method, in which the guidance is only applied to the year of adoption, with the cumulative effect of initially applying the guidance recognized as an adjustment to retained earnings. The Company has elected to follow the modified retrospective method applied to contracts that are not completed as of the date of adoption. The estimated cumulative impact of adopting the standard on January 1, 2018 is an increase in stockholders’ equity of between $70.0 million and $110.0 million .
Consolidation, Policy [Policy Text Block]	Principles of Consolidation The accompanying Consolidated Financial Statements include the accounts of Brown & Brown, Inc. and its subsidiaries. All significant intercompany account balances and transactions have been eliminated in the Consolidated Financial Statements.
Revenue Recognition, Policy [Policy Text Block]	Revenue Recognition Commission revenues are recognized as of the effective date of the insurance policy or the date on which the policy premium is processed into our systems and invoiced to the customer, whichever is later. Commission revenues related to installment billings are recognized on the latter of effective or invoiced date, with the exception of our Arrowhead business which follows a policy of recognizing on the latter of effective or processed date into our systems, regardless of the billing arrangement. Management determines the policy cancellation reserve based upon historical cancellation experience adjusted for any known circumstances. Subsequent commission adjustments were recognized upon our receipt of notification from insurance companies concerning matters necessitating such adjustments. Profit-sharing contingent commissions are recognized when determinable, which is generally when such commissions are received from insurance companies, or when we receive formal notification of the amount of such payments. Fee revenues and commissions for workers’ compensation programs are recognized as services are rendered.
Use of Estimates, Policy [Policy Text Block]	Use of Estimates The preparation of the Consolidated Financial Statements in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, as well as disclosures of contingent assets and liabilities, at the date of the Consolidated Financial Statements, and the reported amounts of revenues and expenses during the reporting period. Actual results may differ from those estimates
Cash and Cash Equivalents, Policy [Policy Text Block]	Cash and Cash Equivalents Cash and cash equivalents principally consist of demand deposits with financial institutions and highly liquid investments with quoted market prices having maturities of three months or less when purchased.
Restricted Cash and Investments Premiums Commissions and Fees Receivable Policy [Text Block]	Restricted Cash and Investments, and Premiums, Commissions and Fees Receivable In our capacity as an insurance agent or broker, the Company typically collects premiums from insureds and, after deducting the authorized commissions, remits the net premiums to the appropriate insurance company or companies. Accordingly, as reported in the Consolidated Balance Sheets, “premiums” are receivable from insureds. Unremitted net insurance premiums are held in a fiduciary capacity until Brown & Brown disburses them. Where allowed by law, Brown & Brown invests these unremitted funds only in cash, money market accounts, tax-free variable-rate demand bonds and commercial paper held for a short term. In certain states in which Brown & Brown operates, the use and investment alternatives for these funds are regulated and restricted by various state laws and agencies. These restricted funds are reported as restricted cash and investments on the Consolidated Balance Sheets. The interest income earned on these unremitted funds, where allowed by state law, is reported as investment income in the Consolidated Statement of Income.
Investment, Policy [Policy Text Block]	Investments Certificates of deposit, and other securities, having maturities of more than three months when purchased are reported at cost and are adjusted for other-than-temporary market value declines.  The Company’s investment holdings include U.S. Government securities, municipal bonds, domestic corporate and foreign corporate bonds as well as short-duration fixed income funds.  Investments within the portfolio or funds are held as available for sale and are carried at their fair value.  Any gain/loss applicable from the fair value change is recorded, net of tax, as other comprehensive income within the equity section of the Consolidated Balance Sheet.  Realized gains and losses are reported on the Consolidated Statement of Income, with the cost of securities sold determined on a specific identification basis
Property, Plant and Equipment, Policy [Policy Text Block]	Fixed Assets Fixed assets, including leasehold improvements, are carried at cost, less accumulated depreciation and amortization. Expenditures for improvements are capitalized, and expenditures for maintenance and repairs are expensed to operations as incurred. Upon sale or retirement, the cost and related accumulated depreciation and amortization are removed from the accounts and the resulting gain or loss, if any, is reflected in other income. Depreciation has been determined using the straight-line method over the estimated useful lives of the related assets, which range from 3 to 15
Goodwill and Intangible Assets, Intangible Assets, Policy [Policy Text Block]	Goodwill and Amortizable Intangible Assets All of our business combinations initiated after June 30, 2001 are accounted for using the acquisition method. Acquisition purchase prices are typically based upon a multiple of average annual operating profit earned over a period of 3 years within a minimum and maximum price range. The recorded purchase prices for all acquisitions consummated after January 1, 2009 include an estimation of the fair value of liabilities associated with any potential earn-out provisions. Subsequent changes in the fair value of earn-out obligations are recorded in the Consolidated Statement of Income when incurred. The fair value of earn-out obligations is based upon the present value of the expected future payments to be made to the sellers of the acquired businesses in accordance with the provisions contained in the respective purchase agreements. In determining fair value, the acquired business’ future performance is estimated using financial projections developed by management for the acquired business and this estimate reflects market participant assumptions regarding revenue growth and/or profitability. The expected future payments are estimated on the basis of the earn-out formula and performance targets specified in each purchase agreement compared to the associated financial projections. These estimates are then discounted to present value using a risk-adjusted rate that takes into consideration the likelihood that the forecasted earn-out payments will be made. Amortizable intangible assets are stated at cost, less accumulated amortization, and consist of purchased customer accounts and non-compete agreements. Purchased customer accounts and non-compete agreements are amortized on a straight-line basis over the related estimated lives and contract periods, which range from 3 to 15 years. Purchased customer accounts primarily consist of records and files that contain information about insurance policies and the related insured parties that are essential to policy renewals. The excess of the purchase price of an acquisition over the fair value of the identifiable tangible and amortizable intangible assets is assigned to goodwill. While goodwill is not amortizable, it is subject to assessment at least annually, and more frequently in the presence of certain circumstances, for impairment by application of a fair value-based test. The Company compares the fair value of each reporting unit with its carrying amount to determine if there is potential impairment of goodwill. If the fair value of the reporting unit is less than its carrying value, an impairment loss is recorded to the extent that the fair value of the goodwill within the reporting unit is less than its carrying value. Fair value is estimated based upon multiples of earnings before interest, income taxes, depreciation, amortization and change in estimated acquisition earn-out payables (“EBITDAC”), or on a discounted cash flow basis. Brown & Brown completed its most recent annual assessment as of November 30, 2017 and determined that the fair value of goodwill significantly exceeded the carrying value of such assets. In addition, as of December 31, 2017, there are no accumulated impairment losses.
Income Tax, Policy [Policy Text Block]	Income Taxes Brown & Brown records income tax expense using the asset-and-liability method of accounting for deferred income taxes. Under this method, deferred tax assets and liabilities are recognized for the expected future tax consequences of temporary differences between the financial statement carrying values and the income tax bases of Brown & Brown’s assets and liabilities.
Share-based Compensation, Option and Incentive Plans Policy [Policy Text Block]	Stock-Based Compensation The Company has granted stock options and grants non-vested stock awards to its employees and officers and fully vested stock awards to directors. The Company uses the modified-prospective method to account for share-based payments. Under the modified-prospective method, compensation cost is recognized for all share-based payments granted on or after January 1, 2006 and for all awards granted to employees prior to January 1, 2006 that remained unvested on that date. The Company uses the alternative-transition method to account for the income tax effects of payments made related to stock-based compensation.
Reinsurance Accounting Policy [Policy Text Block]	Reinsurance The Company protects itself from claims-related losses by reinsuring all claims risk exposure. The only line of insurance the Company underwrites is flood insurance associated with the Wright National Flood Insurance Company (“WNFIC”), which is part of our National Programs Segment. However, all exposure is reinsured with the Federal Emergency Management Agency (“FEMA”) for basic admitted policies conforming to the National Flood Insurance Program. For excess flood insurance policies, all exposure is reinsured with a reinsurance carrier with an AM Best Company rating of “A” or better. Reinsurance does not legally discharge the ceding insurer from the primary liability for the full amount due under the reinsured policies. Reinsurance premiums, commissions, expense reimbursement and reserves related to ceded business are accounted for on a basis consistent with the accounting for the original policies issued and the terms of reinsurance contracts. Premiums earned and losses and loss adjustment expenses incurred are reported net of reinsurance amounts. Other underwriting expenses are shown net of earned ceding commission income. The liabilities for unpaid losses and loss adjustment expenses and unearned premiums are reported gross of ceded reinsurance recoverable.
Unpaid Policy Claims and Claims Adjustment Expense, Policy [Policy Text Block]	Unpaid Losses and Loss Adjustment Reserve Unpaid losses and loss adjustment reserve include amounts determined on individual claims and other estimates based upon the past experience of WNFIC and the policyholders for IBNR claims, less anticipated salvage and subrogation recoverable. The methods of making such estimates and for establishing the resulting reserves are continually reviewed and updated, and any adjustments resulting therefrom are reflected in operations currently.
Insurance Premiums Revenue Recognition, Policy [Policy Text Block]	PremiumsPremiums are recognized as income over the coverage period of the related policies. Unearned premiums represent the portion of premiums written that relate to the unexpired terms of the policies in force and are determined on a daily pro rata basis. The income is recorded to the commissions and fees line of the income statement.
Minimum
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	3 years
Maximum
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	15 years

Nature of Operations (Policies)

Nature of Operations (Policies)	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Operations	Nature of Operations Brown & Brown, Inc., a Florida corporation, and its subsidiaries (collectively, “Brown & Brown” or the “Company”) is a diversified insurance agency, wholesale brokerage, insurance programs and services organization that markets and sells to its customers, insurance products and services, primarily in the property, casualty and employee benefits areas. Brown & Brown’s business is divided into four
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements In November 2016, the Financial Accountings Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2016-18, “Statement of Cash Flows (Topic 230)”: Restricted Cash (“ASU 2016-18”), which requires that the Statement of Cash Flows explain the changes during the period of cash and cash equivalents inclusive of amounts categorized as restricted cash. ASU 2016-18 is effective for periods beginning after December 15, 2017. However, the Company elected to early adopt for the reporting period beginning January 1, 2017 under the full retrospective approach for all periods presented. With the adoption of ASU 2016-18, the change in restricted cash is no longer reflected as a change in operating assets and liabilities, and the Statement of Cash Flows details the changes in the balance of cash and cash equivalents inclusive of restricted cash. Net cash provided by operating activities for the years ended December 31, 2015 and 2016 were previously reported as $411.8 million and $375.2 million , respectively. With the retrospective adoption, the net cash provided by operating activities for the years ended December 31, 2015 and 2016 is now reported as $381.8 million and $411.0 million , respectively. The Company reflects cash collected from customers that is payable to insurance companies as restricted cash if segregation of this cash is required by the state of domicile for the office conducting this transaction or if required by contract with the relevant insurance company providing coverage. Cash collected from customers that is payable to insurance companies is reported in cash and cash equivalents if no such restriction is required. In August 2016, the FASB issued ASU 2016-15, “Statement of Cash Flows (Topic 230)”: Classification of Certain Cash Receipts and Cash Payments (a consensus of the Emerging Issues Task Force) (“ASU 2016-15”), which addresses eight specific cash flow issues with the objective of reducing the existing diversity in practice in how certain cash receipts and cash payments are presented and classified and applies to all entities, including both business entities and not-for-profit entities that are required to present a statement of cash flows under Topic 230. ASU 2016-15 will take effect for public companies for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017 and early adoption is permitted. The Company is adopting this change effective January 1, 2018 and has evaluated the impact of ASU 2016-15 determining that there is no impact on the Company’s Statement of Cash Flows. The Company already presents cash paid on contingent consideration in business combination as prescribed by ASU 2016-15 and does not, at this time, engage in the other activities being addressed. In March 2016, the FASB issued ASU 2016-09, “Improvements to Employee Share Based Payment Accounting” (“ASU 2016-09”), which amends guidance issued in Accounting Standards Codification (“ASC”) Topic 718, Compensation - Stock Compensation. ASU 2016-09 simplifies several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. ASU 2016-09 is effective for fiscal years beginning after December 15, 2016, and interim periods within those fiscal years and early adoption is permitted. The Company adopted the guidance on January 1, 2017, as required. Prior periods have not been adjusted, as the guidance was adopted prospectively. The principal impact is that the tax benefit or expense from stock compensation is now presented in the income tax line of the Statement of Income, whereas the prior treatment was to present this amount as a component of equity on the Balance Sheet. In addition, the tax benefit or expense is now presented as activity in Cash Flow from Operating Activity, rather than the prior presentation as Cash Flow from Financing Activity in the Statement of Cash Flows. The Company also continues to estimate forfeitures of stock grants as allowed by ASU 2016-09. In March 2016, the FASB issued ASU 2016-08, “Principal Versus Agent Considerations (Reporting Revenue Gross Versus Net)” (“ASU 2016-08”) to clarify certain aspects of the principal-versus-agent guidance included in the new revenue standard ASU 2014-09 “Revenue from Contracts with Customers” (“ASU 2014-09”). The FASB issued the ASU in response to concerns identified by stakeholders, including those related to (1) determining the appropriate unit of account under the revenue standard’s principal-versus-agent guidance and (2) applying the indicators of whether an entity is a principal or an agent in accordance with the revenue standard’s control principle. ASU 2016-08 is effective contemporaneous with ASU 2014-09 beginning January 1, 2018. The impact of adopting ASU 2016-08 is not material to the Company. In February 2016, the FASB issued ASU 2016-02, “Leases (Topic 842)” (“ASU 2016-02”), which provides guidance for accounting for leases. Under ASU 2016-02, the Company will be required to recognize the assets and liabilities for the rights and obligations created by leased assets. ASU 2016-02 will take effect for public companies for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. The Company continues to evaluate the impact of this pronouncement with the principal impact being that the present value of the remaining lease payments be presented as a liability on the Balance Sheet as well as an asset of similar value representing the “Right of Use” for those leased properties. As detailed in Note 13 of the 2016 10-K, the undiscounted contractual cash payments remaining on leased properties was $213.2 million as of December 31, 2016 and is $210.4 million as of December 31, 2017 as detailed in “Management’s Discussion and Analysis of Financial Condition and Results of Operations - Liquidity and Capital Resources” and Note 13 “Commitments and Contingencies.” In November 2015, FASB issued ASU No. 2015-17, “Income Taxes (Topic 740) - Balance Sheet Classification of Deferred Taxes” (“ASU 2015-17”), which simplifies the presentation of deferred income taxes by requiring deferred tax assets and liabilities be classified as a single non-current item on the balance sheet. ASU 2015-17 is effective for fiscal years beginning after December 15, 2016 with early adoption permitted as of the beginning of any interim or annual reporting period. The Company adopted the guidance on January 1, 2017, as required. As a result, the Company retrospectively applied the guidance to the 2016 balance sheet by reclassifying $24.6 million from deferred income taxes (asset) to deferred income taxes, net (liability) on the Condensed Consolidated Balance Sheet. This reclassification occurred prior to the passage of the Tax Cuts and Jobs Act of 2017, which had a material impact on the value of deferred tax items. See Note 9 “Income Taxes” for more information. In May 2014, FASB issued ASU No. 2014-09, “Revenue from Contracts with Customers (Topic 606)” (“Topic 606”), which provides guidance for revenue recognition. Topic 606 affects any entity that either enters into contracts with customers to transfer goods or services or enters into contracts for the transfer of non-financial assets. It supersedes the revenue recognition requirements in Topic 605, “Revenue Recognition,” and most industry-specific guidance. The standard’s core principle is that a company should recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which a company expects to be entitled in exchange for those goods or services. In doing so, companies will need to use more judgment and make more estimates than under the current guidance. Specifically, in situations where multiple performance obligations exist within a contract, the use of estimates is required to allocate the transaction price to each separate performance obligation. Historically, approximately 70% of the Company’s commissions and fees are in the form of commissions paid by insurance carriers. These commissions are earned upon the effective date of bound coverage, as no significant performance obligation remains after coverage is bound. The following areas are impacted by the adoption of Topic 606: Installment billing - Prior to the adoption of Topic 606, commission revenues related to installment billings were recognized on the latter of the policy effective date (as indicated in the policy) or the date that the premium was billed to the client (as indicated on the premium invoice), with the exception of our Arrowhead businesses, which follow a policy of recognizing these revenues on the latter of the policy effective date or processed date into our systems, regardless of the billing arrangement. As a result of the adoption of Topic 606, revenue associated with the issuance of policies will be recognized upon the effective date of the associated policy, which means that commission revenues billed on an installment basis will be now recognized earlier than they had been previously resulting in revenue will accrued based upon the completion of the performance obligation and thus creating a current asset for the unbilled revenue until such time as an invoice is generated, typically not to exceed twelve months. The Company does not expect the overall impact of these changes to be significant on a full-year basis, but the timing of recognizing revenue will be impacted among quarters when compared to prior years. Contingent commissions - Prior to the adoption of Topic 606, revenue that was not fixed and determinable because a contingency exists was not recognized until the contingency was resolved. Under Topic 606, the Company must use its judgment to estimate the amount of consideration that will be received such that a significant reversal of revenue is not probable. Contingent commissions represent a form of variable consideration associated with the same performance obligation, which is the placement of coverage, for which we earn core commissions. In connection with the new standard, contingent commissions will be estimated with an appropriate constraint applied and accrued relative to the recognition of the corresponding core commissions. The resulting effect on the timing of recognition of contingent commissions will more closely follow a similar pattern as our core commissions with true-ups recognized when payments are received or as additional information that affects the estimate becomes available. Contingent commissions have averaged approximately 3.6% of the previous year’s total commissions and fees over the last three years and have primarily been received in the first and second quarters of the year. Approximately 30% of the Company’s commissions and fees is in the form of fees, which are predominantly in our National Programs and Services Segments, and to a lesser extent in the large accounts business within our Retail Segment, where we receive fees in lieu of a commission. In accordance with Topic 606, fee revenue from certain agreements will be recognized in earlier periods and others in later periods as compared to our current accounting treatment. The Company does not expect the overall impact of these changes to be significant on a full-year basis, but the timing of recognizing revenue will be impacted among quarters when compared to prior years. Additionally, the Company has evaluated ASC Topic 340 - Other Assets and Deferred Cost (“ASC 340”) which requires companies to defer certain incremental costs to obtain customer contracts, and certain costs to fulfill customer contracts. Incremental cost to obtain - the adoption of ASC 340 will result in the Company deferring certain cost to obtain customer contracts primarily as they relate to commission based compensation plans in the Retail Segment, in which the Company pays an incremental amount of compensation on new business in the first year of the contract. These incremental costs will be deferred and amortized over a 15-year period, which is consistent with the analysis performed on acquired customer accounts and referenced in Note 4 to the Company’s financial statements. Cost to fulfill - the adoption of ASC 340 will result in the Company deferring certain costs to fulfill a contract and recognize these costs as the associated performance obligations are fulfilled. In order for contract fulfillment costs to be deferred under ASC 340, the costs must (1) relate directly to a specific contract or anticipated contract, (2) generate or enhance resources that the Company will use in satisfying its obligations under the contract, and (3) be expected to be recovered through sufficient net cash flows from the contract. The Company does not expect the overall impact of these changes to be significant on a full-year basis, but the timing of recognizing these expenses will be impacted among quarters to better align with the associated revenue. Topic 606 is effective for the Company beginning January 1, 2018. Entities are permitted to adopt the guidance under one of the following methods: the “full retrospective” method, which applies the guidance to each period presented (prior years restated), or the “modified retrospective” method, in which the guidance is only applied to the year of adoption, with the cumulative effect of initially applying the guidance recognized as an adjustment to retained earnings. The Company has elected to follow the modified retrospective method applied to contracts that are not completed as of the date of adoption. The estimated cumulative impact of adopting the standard on January 1, 2018 is an increase in stockholders’ equity of between $70.0 million and $110.0 million .

Net Income Per Share (Tables)

Net Income Per Share (Tables)	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Reconciliation between Basic and Diluted Weighted Average Shares Outstanding	The following is a reconciliation between basic and diluted weighted-average shares outstanding for the years ended December 31 : (in thousands, except per share data) 2017 2016 2015 Net income $ 399,630 $ 257,491 $ 243,318 Net income attributable to unvested awarded performance stock (9,746 ) (6,705 ) (5,695 ) Net income attributable to common shares $ 389,884 $ 250,786 $ 237,623 Weighted-average number of common shares outstanding – basic 139,697 139,779 141,113 Less unvested awarded performance stock included in weighted-average number of common shares outstanding – basic (3,407 ) (3,640 ) (3,303 ) Weighted-average number of common shares outstanding for basic earnings per common share 136,290 136,139 137,810 Dilutive effect of stock options 2,503 1,665 2,302 Weighted-average number of shares outstanding – diluted 138,793 137,804 140,112 Net income per share: Basic $ 2.86 $ 1.84 $ 1.72 Diluted $ 2.81 $ 1.82 $ 1.70

Business Combinations (Tables)

Business Combinations (Tables)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Business Combinations [Abstract]
Purchase price allocation for current year acquisitions and adjustments made for prior year acquisitions	(in thousands) Name Business Effective Cash Other Recorded Net Assets Maximum Other Various Various $ 41,471 $ 11,708 $ 6,921 $ 60,100 $ 27,451 Total $ 41,471 $ 11,708 $ 6,921 $ 60,100 $ 27,451	The following table summarizes the purchase price allocation made as of the date of each acquisition for current year acquisitions and significant adjustments made during the measurement period for prior year acquisitions: (in thousands) Name Business Effective Cash Note Payable Other Recorded Net Assets Maximum Social Security Advocates for the Disabled LLC (SSAD) Services February 1, 2016 $ 32,526 $ 492 $ — $ 971 $ 33,989 $ 3,500 Morstan General Agency, Inc. (Morstan) Wholesale Brokerage June 1, 2016 66,050 — 10,200 3,091 79,341 5,000 Other Various Various 26,140 — 464 400 27,004 7,785 Total $ 124,716 $ 492 $ 10,664 $ 4,462 $ 140,334 $ 16,285	The following table summarizes the purchase price allocation made as of the date of each acquisition for current year acquisitions and significant adjustments made during the measurement period for prior year acquisitions: (in thousands) Name Business Segment Effective Date of Acquisition Cash Paid Other Payable Recorded Earn-Out Payable Net Assets Acquired Maximum Potential Earn- Out Payable Liberty Insurance Brokers, Inc. and Affiliates (Liberty) Retail February 1, 2015 $ 12,000 $ — $ 2,981 $ 14,981 $ 3,750 Spain Agency, Inc. (Spain) Retail March 1, 2015 20,706 — 2,617 23,323 9,162 Bellingham Underwriters, Inc. (Bellingham) National Programs May 1, 2015 9,007 500 3,322 12,829 4,400 Fitness Insurance, LLC (Fitness) Retail June 1, 2015 9,455 — 2,379 11,834 3,500 Strategic Benefit Advisors, Inc. (SBA) Retail June 1, 2015 49,600 400 13,587 63,587 26,000 Bentrust Financial, Inc. (Bentrust) Retail December 1, 2015 10,142 391 319 10,852 2,200 MBA Insurance Agency of Arizona, Inc. (MBA) Retail December 1, 2015 68 8,442 6,063 14,573 9,500 Smith Insurance, Inc. (Smith) Retail December 1, 2015 12,096 200 1,047 13,343 6,350 Other Various Various 12,926 95 4,584 17,605 8,212 Total $ 136,000 $ 10,028 $ 36,899 $ 182,927 $ 73,074
Estimated fair values of aggregate assets and liabilities acquired	The following table summarizes the estimated fair values of the aggregate assets and liabilities acquired as of the date of each acquisition. (in thousands) Total Other current assets $ 601 Fixed assets 69 Goodwill 42,172 Purchased customer accounts 18,738 Non-compete agreements 721 Total assets acquired 62,301 Other current liabilities (1,512 ) Deferred income tax, net (689 ) Total liabilities assumed (2,201 ) Net assets acquired $ 60,100	The following table summarizes the estimated fair values of the aggregate assets and liabilities acquired as of the date of each acquisition. (in thousands) SSAD Morstan Other Total Cash $ 2,094 $ — $ — $ 2,094 Other current assets 1,042 2,482 1,555 5,079 Fixed assets 307 300 77 684 Goodwill 22,352 51,454 19,570 93,376 Purchased customer accounts 13,069 26,481 11,075 50,625 Non-compete agreements 72 39 117 228 Other assets — — 20 20 Total assets acquired 38,936 80,756 32,414 152,106 Other current liabilities (1,717 ) (1,415 ) (5,410 ) (8,542 ) Deferred income tax, net (3,230 ) — — (3,230 ) Total liabilities assumed (4,947 ) (1,415 ) (5,410 ) (11,772 ) Net assets acquired $ 33,989 $ 79,341 $ 27,004 $ 140,334	The following table summarizes the estimated fair values of the aggregate assets and liabilities acquired as of the date of each acquisition. The data included in the “Other” column shows a negative adjustment for purchased customer accounts. This is driven mainly by the final valuation adjustment for the acquisition of Wright. (in thousands) Liberty Spain Bellingham Fitness SBA Bentrust MBA Smith Other Total Other current assets $ 2,486 $ 324 $ — $ 9 $ 652 $ — $ — $ — $ 169 $ 3,640 Fixed assets 40 50 25 17 41 36 33 73 59 374 Goodwill 10,010 15,748 9,608 8,105 39,859 8,166 13,471 10,374 21,040 136,381 Purchased customer accounts 4,506 7,430 3,223 3,715 23,000 2,789 7,338 3,526 (2,135 ) 53,392 Non-compete agreements 24 21 21 — 21 43 11 31 156 328 Other assets — — — — 14 — — — — 14 Total assets acquired 17,066 23,573 12,877 11,846 63,587 11,034 20,853 14,004 19,289 194,129 Other current liabilities (42 ) (250 ) (48 ) (12 ) — (182 ) (6,280 ) (504 ) (4,895 ) (12,213 ) Deferred income tax, net — — — — — — — — 2,576 2,576 Other liabilities (2,043 ) — — — — — — (157 ) 635 (1,565 ) Total liabilities assumed (2,085 ) (250 ) (48 ) (12 ) — (182 ) (6,280 ) (661 ) (1,684 ) (11,202 ) Net assets acquired $ 14,981 $ 23,323 $ 12,829 $ 11,834 $ 63,587 $ 10,852 $ 14,573 $ 13,343 $ 17,605 $ 182,927
Unaudited pro forma results	These unaudited pro forma results are not necessarily indicative of the actual results of operations that would have occurred had the acquisitions actually been made at the beginning of the respective periods. (UNAUDITED) For the Year Ended December 31, (in thousands, except per share data) 2017 2016 Total revenues $ 1,891,701 $ 1,784,776 Income before income taxes $ 453,397 $ 429,490 Net income $ 401,908 $ 261,133 Net income per share: Basic $ 2.88 $ 1.87 Diluted $ 2.83 $ 1.85 Weighted-average number of shares outstanding: Basic 136,290 136,139 Diluted 138,793 137,804	These unaudited pro forma results are not necessarily indicative of the actual results of operations that would have occurred had the acquisitions actually been made at the beginning of the respective periods. (UNAUDITED) For the Year Ended December 31, (in thousands, except per share data) 2016 2015 Total revenues $ 1,789,790 $ 1,716,592 Income before income taxes $ 428,194 $ 414,911 Net income $ 260,346 $ 250,783 Net income per share: Basic $ 1.86 $ 1.78 Diluted $ 1.84 $ 1.75 Weighted-average number of shares outstanding: Basic 136,139 137,810 Diluted 137,804 140,112	These unaudited pro forma results are not necessarily indicative of the actual results of operations that would have occurred had the acquisitions actually been made at the beginning of the respective periods. (UNAUDITED) For the Year Ended December 31, (in thousands, except per share data) 2015 Total revenues $ 1,688,297 Income before income taxes $ 411,497 Net income $ 248,720 Net income per share: Basic $ 1.76 Diluted $ 1.73 Weighted-average number of shares outstanding: Basic 137,810 Diluted 140,112
Schedule Of Business Acquisition Estimated Earn Out Payables Table [Text Block]	The resulting additions, payments and net changes, as well as the interest expense accretion on the estimated acquisition earn-out payables, for the years ended December 31, 2017 , 2016 and 2015 were as follows: For the Year Ended December 31, (in thousands) 2017 2016 2015 Balance as of the beginning of the period $ 63,821 $ 78,387 $ 75,283 Additions to estimated acquisition earn-out payables 6,920 4,462 36,899 Payments for estimated acquisition earn-out payables (43,766 ) (28,213 ) (36,798 ) Subtotal 26,975 54,636 75,384 Net change in earnings from estimated acquisition earn-out payables: Change in fair value on estimated acquisition earn-out payables 6,874 6,338 13 Interest expense accretion 2,326 2,847 2,990 Net change in earnings from estimated acquisition earn-out payables 9,200 9,185 3,003 Balance as of December 31, $ 36,175 $ 63,821 $ 78,387

Goodwill (Tables)

Goodwill (Tables)	12 Months Ended
	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Changes in Carrying Value of Goodwill by Operating Segment	The changes in the carrying value of goodwill by reportable segment for the years ended December 31, are as follows: (in thousands) Retail National Programs Wholesale Brokerage Services Total Balance as of January 1, 2016 $ 1,345,636 $ 901,866 $ 226,961 $ 112,220 $ 2,586,683 Goodwill of acquired businesses 13,117 (1 ) 57,908 22,352 93,376 Goodwill of transferred businesses 571 (571 ) — — — Goodwill disposed of relating to sales of businesses (4,657 ) — — — (4,657 ) Balance as of December 31, 2016 $ 1,354,667 $ 901,294 $ 284,869 $ 134,572 $ 2,675,402 Goodwill of acquired businesses 33,076 7,178 1,229 689 42,172 Goodwill disposed of relating to sales of businesses (1,495 ) — — — (1,495 ) Balance as of December 31, 2017 $ 1,386,248 $ 908,472 $ 286,098 $ 135,261 $ 2,716,079

Amortizable Intangible Assets (

Amortizable Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Amortizable Intangible Assets	Amortizable intangible assets at December 31, 2017 and 2016 consisted of the following: December 31, 2017 December 31, 2016 (in thousands) Gross Carrying Value Accumulated Amortization Net Carrying Value Weighted Average Life in Years (1) Gross Carrying Value Accumulated Amortization Net Carrying Value Weighted Average Life in Years (1) Purchased customer accounts $ 1,464,274 $ (824,584 ) $ 639,690 15.0 $ 1,447,680 $ (741,770 ) $ 705,910 15.0 Non-compete agreements 30,287 (28,972 ) 1,315 6.8 29,668 (28,124 ) 1,544 6.8 Total $ 1,494,561 $ (853,556 ) $ 641,005 $ 1,477,348 $ (769,894 ) $ 707,454 (1)

Investments (Tables)

Investments (Tables)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Investments, Debt and Equity Securities [Abstract]
Schedule of Investments in Fixed Maturity Securities	At December 31, 2017 , the Company’s amortized cost and fair values of fixed maturity securities are summarized as follows: (in thousands) Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value U.S. Treasury securities, obligations of U.S. Government agencies and Municipalities $ 29,970 $ — $ (206 ) $ 29,764 Corporate debt 1,072 12 — 1,084 Total $ 31,042 $ 12 $ (206 ) $ 30,848 At December 31, 2017 , the Company held $30.0 million in fixed income securities composed of U.S Treasury securities, securities issued by U.S. Government agencies and Municipalities, and $1.1 million issued by corporations with investment-grade ratings. Of the total, $16.9 million is classified as short-term investments on the Consolidated Balance Sheet as maturities are less than one year in duration. Additionally, the Company holds $8.1 million	At December 31, 2016 , the Company’s amortized cost and fair values of fixed maturity securities are summarized as follows: (in thousands) Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value U.S. Treasury securities, obligations of U.S. Government agencies and Municipalities $ 26,280 $ 11 $ (59 ) $ 26,232 Corporate debt 2,358 13 (1 ) 2,370 Total $ 28,638 $ 24 $ (60 ) $ 28,602
Summary of Unrealized Loss Position	For securities in a loss position, the following table shows the investments’ gross unrealized loss and fair value, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position as of December 31, 2017 : (in thousands) Less than 12 Months 12 Months or More Total Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses U.S. Treasury securities, obligations of U.S. Government agencies and Municipalities $ 17,919 $ (157 ) $ 11,845 $ (49 ) $ 29,764 $ (206 ) Corporate debt 400 — — — 400 — Total $ 18,319 $ (157 ) $ 11,845 $ (49 ) $ 30,164 $ (206 )	The following table shows the investments’ gross unrealized loss and fair value, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position as of December 31, 2016 : (in thousands) Less than 12 Months 12 Months or More Total Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses U.S. Treasury securities, obligations of U.S. Government agencies and Municipalities $ 14,663 $ (59 ) $ — $ — $ 14,663 $ (59 ) Corporate debt 1,001 (1 ) — — 1,001 (1 ) Total $ 15,664 $ (60 ) $ — $ — $ 15,664 $ (60 )
Amortized Cost and Fair Value of Fixed Maturity Securities by Contractual Maturity	The amortized cost and estimated fair value of the fixed maturity securities at December 31, 2017 by contractual maturity are set forth below: (in thousands) Amortized Cost Fair Value Years to maturity: Due in one year or less $ 16,934 $ 16,899 Due after one year through five years 13,876 13,708 Due after five years through ten years 232 241 Total $ 31,042 $ 30,848	The amortized cost and estimated fair value of the fixed maturity securities at December 31, 2016 by contractual maturity are set forth below: (in thousands) Amortized Cost Fair Value Years to maturity: Due in one year or less $ 5,551 $ 5,554 Due after one year through five years 22,757 22,708 Due after five years through ten years 330 340 Total $ 28,638 $ 28,602

Fixed Assets (Tables)

Fixed Assets (Tables)	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment [Table Text Block]	Fixed assets at December 31 consisted of the following: (in thousands) 2017 2016 Furniture, fixtures and equipment $ 190,784 $ 177,823 Leasehold improvements 35,481 33,137 Land, buildings and improvements 7,643 3,375 Total cost 233,908 214,335 Less accumulated depreciation and amortization (156,822 ) (138,528 ) Total $ 77,086 $ 75,807 Depreciation and amortization expense for fixed assets amounted to $22.7 million in 2017 , $21.0 million in 2016 and $20.9 million in 2015

Accrued Expenses (Tables)

Accrued Expenses (Tables) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Payables and Accruals [Abstract]
Other Current Liabilities [Table Text Block]	$ 10,951	$ 11,726
Accrued expenses and other liabilities	228,748	201,989
Interest Payable, Current	6,749	6,441
Reserve for policy cancellations	11,048	9,567
Accrued Rent and Vendor Expenses	30,616	28,669
Accrued Employee Benefits, Current	40,540	45,771
Accrued Bonuses	$ 106,923	82,438
Accounts Payable, Accrued Liabilities, and Other Liabilities Disclosure, Current [Text Block]	Accrued Expenses and Other Liabilities Accrued expenses and other liabilities at December 31 consisted of the following: (in thousands) 2017 2016 Accrued incentive compensation $ 106,923 $ 82,438 Accrued compensation and benefits 40,540 45,771 Accrued rent and vendor expenses 30,616 28,669 Deferred revenue 21,921 17,377 Reserve for policy cancellations 11,048 9,567 Accrued interest 6,749 6,441 Other 10,951 11,726 Total $ 228,748 $ 201,989
Schedule of Accrued Liabilities [Table Text Block]	Accrued expenses and other liabilities at December 31 consisted of the following: (in thousands) 2017 2016 Accrued incentive compensation $ 106,923 $ 82,438 Accrued compensation and benefits 40,540 45,771 Accrued rent and vendor expenses 30,616 28,669 Deferred revenue 21,921 17,377 Reserve for policy cancellations 11,048 9,567 Accrued interest 6,749 6,441 Other 10,951 11,726 Total $ 228,748 $ 201,989
Deferred Revenue	$ 21,921	$ 17,377

Long-Term Debt (Tables)

Long-Term Debt (Tables)	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Long-Term Debt Instrument	Long-term debt at December 31, 2017 and 2016 consisted of the following: (in thousands) December 31, 2017 December 31, 2016 Current portion of long-term debt: Current portion of 5-year term loan facility expires 2019 $ 20,000 $ 55,000 4.500% senior notes, Series E, quarterly interest payments, balloon due 2018 100,000 — Short-term promissory note — 500 Total current portion of long-term debt 120,000 55,500 Long-term debt: Note agreements: 4.500% senior notes, Series E, quarterly interest payments, balloon due 2018 — 100,000 4.200% senior notes, semi-annual interest payments, balloon due 2024 498,943 498,785 Total notes 498,943 598,785 Credit agreements: 5-year term loan facility, periodic interest and principal payments, LIBOR plus up to 1.750%, expires June 28, 2022 365,000 426,250 5-year revolving loan facility, periodic interest payments, currently LIBOR plus up to 1.500%, plus commitment fees up to 0.250%, expires June 28, 2022 — — Total credit agreements 365,000 426,250 Debt issuance costs (contra) (7,802 ) (6,663 ) Total long-term debt less unamortized discount and debt issuance costs 856,141 1,018,372 Current portion of long-term debt 120,000 55,500 Total debt $ 976,141 $ 1,073,872

Income Taxes (Tables)

Income Taxes (Tables) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Contingency [Line Items]
Schedule of Deferred Tax Assets and Liabilities [Table Text Block]	ignificant components of Brown & Brown’s net deferred tax liabilities as of December 31 are as follows: (in thousands) 2017 2016 Non-current deferred tax liabilities: Intangible assets $ 306,351 $ 422,478 Fixed assets 2,723 6,425 Net unrealized holding (loss)/gain on available-for-sale securities (6 ) (12 ) Total non-current deferred tax liabilities 309,068 428,891 Non-current deferred tax assets: Deferred compensation 36,701 44,912 Accruals and reserves 7,534 14,032 Deferred profit-sharing contingent commissions 7,107 10,567 Net operating loss carryforwards 2,434 2,394 Valuation allowance for deferred tax assets (893 ) (700 ) Total non-current deferred tax assets 52,883 71,205 Net non-current deferred tax liability $ 256,185 $ 357,686
Income Tax Disclosure [Text Block]	Income Taxes On December 22, 2017, the U.S. government enacted the Tax Cuts and Jobs Act of 2017 (the “Tax Reform Act”). The Tax Reform Act makes broad and complex changes to the U.S. tax code that affected our income tax rate in 2017. The Tax Reform Act reduces the U.S. federal corporate income tax rate from 35.0% to 21.0% and requires companies to pay a one-time transition tax on certain unrepatriated earnings from foreign subsidiaries that is payable over eight years. The Tax Reform Act also establishes new tax laws that became effective January 1, 2018. ASC 740 requires a company to record the effects of a tax law change in the period of enactment, however, shortly after the enactment of the Tax Reform Act, the SEC staff issued SAB 118, which allows a company to record a provisional amount when it does not have the necessary information available, prepared, or analyzed in reasonable detail to complete its accounting for the change in the tax law. The measurement period ends when the company has obtained, prepared and analyzed the information necessary to finalize its accounting, but cannot extend beyond one year. We have made a reasonable estimate of the impact of the Tax Reform Act and recorded a one-time credit in our 2017 income tax expense of $120.9 million , which reflects an estimated reduction in our deferred income tax liabilities of $124.2 million as a result of the maximum federal rate decreasing to 21.0% from 35.0% , which was partially offset by an estimated increase in income tax payable in the amount of $3.3 million as a result of the transition tax on cash and cash equivalent balances related to untaxed accumulated earnings associated with our international operations. We are continuing to gather additional information related to estimates surrounding the re-measurement of our deferred tax liabilities and the transition tax on unrepatriated earnings. Significant components of the provision for income taxes for the years ended December 31 are as follows: (in thousands) 2017 2016 2015 Current: Federal $ 129,954 $ 126,145 $ 118,490 State 21,392 21,110 17,625 Foreign 929 590 430 Total current provision 152,275 147,845 136,545 Deferred: Federal 18,999 15,551 18,416 State 2,984 2,612 4,280 Foreign — — — Tax Reform Act deferred tax revaluation (124,166 ) — — Total deferred provision (102,183 ) 18,163 22,696 Total tax provision $ 50,092 $ 166,008 $ 159,241 A reconciliation of the differences between the effective tax rate and the federal statutory tax rate for the years ended December 31 is as follows: 2017 2016 2015 Federal statutory tax rate 35.0% 35.0% 35.0% State income taxes, net of federal income tax benefit 3.8 3.9 3.9 Non-deductible employee stock purchase plan expense 0.3 0.3 0.3 Non-deductible meals and entertainment 0.3 0.3 0.3 Tax Reform Act deferred tax revaluation and transition tax impact (26.9) — — Other, net (1.4) (0.3) 0.1 Effective tax rate 11.1% 39.2% 39.6% Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the corresponding amounts used for income tax reporting purposes. Significant components of Brown & Brown’s net deferred tax liabilities as of December 31 are as follows: (in thousands) 2017 2016 Non-current deferred tax liabilities: Intangible assets $ 306,351 $ 422,478 Fixed assets 2,723 6,425 Net unrealized holding (loss)/gain on available-for-sale securities (6 ) (12 ) Total non-current deferred tax liabilities 309,068 428,891 Non-current deferred tax assets: Deferred compensation 36,701 44,912 Accruals and reserves 7,534 14,032 Deferred profit-sharing contingent commissions 7,107 10,567 Net operating loss carryforwards 2,434 2,394 Valuation allowance for deferred tax assets (893 ) (700 ) Total non-current deferred tax assets 52,883 71,205 Net non-current deferred tax liability $ 256,185 $ 357,686 Income taxes paid in 2017 , 2016 and 2015 were $152.0 million , $143.1 million and $132.9 million , respectively. At December 31, 2017 , Brown & Brown had net operating loss carryforwards of $0.1 million and $52.2 million for federal and state income tax reporting purposes, respectively, portions of which expire in the years 2018 through 2037 . The federal carryforward is derived from insurance operations acquired by Brown & Brown in 2001. The state carryforward amount is derived from the operating results of certain subsidiaries and from the 2013 stock acquisition of Beecher Carlson Holdings, Inc. A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows: (in thousands) 2017 2016 2015 Unrecognized tax benefits balance at January 1 $ 750 $ 584 $ 113 Gross increases for tax positions of prior years 1,070 412 773 Gross decreases for tax positions of prior years — (41 ) — Settlements (126 ) (205 ) (302 ) Unrecognized tax benefits balance at December 31 $ 1,694 $ 750 $ 584 The Company recognizes interest and penalties related to uncertain tax positions in income tax expense. As of December 31, 2017 , 2016 and 2015 the Company had $228,608 , $86,191 and $102,171 of accrued interest and penalties related to uncertain tax positions, respectively. The total amount of unrecognized tax benefits that would affect the Company’s effective tax rate if recognized was $1.7 million as of December 31, 2017 , $750,258 as of December 31, 2016 and $583,977 as of December 31, 2015 . The Company does not expect its unrecognized tax benefits to change significantly over the next 12 months. As a result of a 2006 Internal Revenue Service (“IRS”) audit, the Company agreed to accrue at each December 31, for tax purposes only, a known amount of profit-sharing contingent commissions represented by the actual amount of profit-sharing contingent commissions received in the first quarter of the related year, with a true-up adjustment to the actual amount received by the end of the following March. Since this method for tax purposes differs from the method used for book purposes, it will result in a current deferred tax asset as of December 31 each year which will reverse by the following March 31 when the related profit-sharing contingent commissions are recognized for financial accounting purposes. The Company is subject to taxation in the United States and various state jurisdictions. The Company is also subject to taxation in the United Kingdom. In the United States, federal returns for fiscal years 2013 through 2016 remain open and subject to examination by the IRS. The Company files and remits state income taxes in various states where the Company has determined it is required to file state income taxes. The Company’s filings with those states remain open for audit for the fiscal years 2011 through 2017. In the United Kingdom, the Company’s filings remain open for audit for the fiscal years 2016 and 2017. During 2017, the Company settled the previously disclosed IRS income tax audit of The Wright Insurance Group for the short period ended May 1, 2014. Pursuant to the agreement in which the Company acquired The Wright Insurance Group, the Company was fully indemnified for all audit-related assessments. The Company and one of its subsidiaries, The Advocator Group, LLC, is currently under examination by the State of Massachusetts for the fiscal year 2013 through 2014. There are no other federal or state income tax audits as of December 31, 2017 . As a result of the Tax Reform Act, the Company has recorded a transition tax of $3.2 million . As of December 31, 2017, the Company has estimated $20.9 million
Summary of Income Tax Contingencies [Table Text Block]	$ (102,183)	$ 18,163	$ 22,696
Summary of Positions for which Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Table Text Block]	A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows: (in thousands) 2017 2016 2015 Unrecognized tax benefits balance at January 1 $ 750 $ 584 $ 113 Gross increases for tax positions of prior years 1,070 412 773 Gross decreases for tax positions of prior years — (41 ) — Settlements (126 ) (205 ) (302 ) Unrecognized tax benefits balance at December 31 $ 1,694 $ 750 $ 584
Schedule of Components of Income Tax Expense (Benefit) [Table Text Block]	Significant components of the provision for income taxes for the years ended December 31 are as follows: (in thousands) 2017 2016 2015 Current: Federal $ 129,954 $ 126,145 $ 118,490 State 21,392 21,110 17,625 Foreign 929 590 430 Total current provision 152,275 147,845 136,545 Deferred: Federal 18,999 15,551 18,416 State 2,984 2,612 4,280 Foreign — — — Tax Reform Act deferred tax revaluation (124,166 ) — — Total deferred provision (102,183 ) 18,163 22,696 Total tax provision $ 50,092 $ 166,008 $ 159,241

Income Taxes Tax Rate (Tables)

Income Taxes Tax Rate (Tables)	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]	A reconciliation of the differences between the effective tax rate and the federal statutory tax rate for the years ended December 31 is as follows: 2017 2016 2015 Federal statutory tax rate 35.0% 35.0% 35.0% State income taxes, net of federal income tax benefit 3.8 3.9 3.9 Non-deductible employee stock purchase plan expense 0.3 0.3 0.3 Non-deductible meals and entertainment 0.3 0.3 0.3 Tax Reform Act deferred tax revaluation and transition tax impact (26.9) — — Other, net (1.4) (0.3) 0.1 Effective tax rate 11.1% 39.2% 39.6%

Stock Based Compensation (Table

Stock Based Compensation (Tables) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation	$ 30,631	$ 16,052	$ 15,513
Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block]	A summary of stock option activity for the years ended December 31, 2017 , 2016 and 2015 is as follows: Stock Options Shares Under Option Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term (in years) Aggregate Intrinsic Value (in thousands) Outstanding at January 1, 2015 470,356 $ 18.57 3.1 $ 5,087 Granted — $ — Exercised (151,767 ) $ 18.48 Forfeited (49,000 ) $ 19.36 Expired — $ — Outstanding at December 31, 2015 269,589 $ 18.48 2.2 $ 2,395 Granted — $ — Exercised (64,589 ) $ 18.48 Forfeited (30,000 ) $ 18.48 Expired — $ — Outstanding at December 31, 2016 175,000 $ 18.48 1.2 $ 4,616 Granted — $ — Exercised (175,000 ) $ 18.48 Forfeited — $ — Expired — $ — Outstanding at December 31, 2017 — $ — N/A $ — Ending vested and expected to vest at December 31, — $ — N/A $ — Exercisable at December 31, 2017 — $ — N/A $ — Exercisable at December 31, 2016 175,000 $ 18.48 1.2 $ 4,616 Exercisable at December 31, 2015 164,589 $ 18.48 2.2 $ 2,241 December 31, 2017 , 2016 and 2015 is as follows: Weighted- Average Grant Date Fair Value Granted Shares Awarded Shares Shares Not Yet Awarded Outstanding at January 1, 2015 $ 28.19 6,659,047 1,060,890 5,598,157 Granted $ 31.74 481,166 164,646 316,520 Awarded $ — — — — Vested $ — — — — Forfeited $ 26.32 (863,241 ) (95,542 ) (767,699 ) Outstanding at December 31, 2015 $ 28.74 6,276,972 1,129,994 5,146,978 Granted $ 35.52 972,099 182,653 789,446 (1) Awarded $ 24.93 — 1,431,319 (1,431,319 ) Vested $ 27.31 (166,884 ) (166,884 ) — Forfeited $ 25.34 (954,131 ) (175,788 ) (778,343 ) Outstanding at December 31, 2016 $ 29.96 6,128,056 2,401,294 3,726,762 Granted $ 41.65 696,456 120,667 575,789 (2) Awarded $ 31.44 — 163,404 (163,404 ) Vested $ 25.22 (242,457 ) (242,457 ) — Forfeited $ 29.77 (171,060 ) (38,106 ) (132,954 ) Outstanding at December 31, 2017 $ 31.16 6,410,995 2,404,802 4,006,193 December 31, 2017 , 2016 and 2015 is as follows: Weighted- Average Grant Date Fair Value Granted Shares Awarded Shares Shares Not Yet Awarded Outstanding at January 1, 2015 $ 8.71 1,928,631 1,903,213 25,418 Granted $ — — — — Awarded $ — — — — Vested $ 5.55 (208,889 ) (208,889 ) — Forfeited $ 9.78 (117,528 ) (100,110 ) (17,418 ) Outstanding at December 31, 2015 $ 9.03 1,602,214 1,594,214 8,000 Granted $ — — — — Awarded $ — — 4,000 (4,000 ) Vested $ 6.39 (506,422 ) (506,422 ) — Forfeited $ 10.52 (92,517 ) (88,517 ) (4,000 ) Outstanding at December 31, 2016 $ 10.23 1,003,275 1,003,275 — Granted $ — — — — Awarded $ — — — — Vested $ 9.61 (138,801 ) (138,801 ) — Forfeited $ 10.47 (17,236 ) (17,236 ) — Outstanding at December 31, 2017 $ 10.32 847,238 847,238 —
Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation	$ 24,899	11,049	11,111
PerformanceStock​Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation	1,707	1,305	972
Employee Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation	$ 4,025	$ 3,698	$ 3,430

Stock Based Compensation Summar

Stock Based Compensation Summary of Stock Based Compensation Plan Activity (Tables)	12 Months Ended
	Dec. 31, 2017
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block]	A summary of stock option activity for the years ended December 31, 2017 , 2016 and 2015 is as follows: Stock Options Shares Under Option Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term (in years) Aggregate Intrinsic Value (in thousands) Outstanding at January 1, 2015 470,356 $ 18.57 3.1 $ 5,087 Granted — $ — Exercised (151,767 ) $ 18.48 Forfeited (49,000 ) $ 19.36 Expired — $ — Outstanding at December 31, 2015 269,589 $ 18.48 2.2 $ 2,395 Granted — $ — Exercised (64,589 ) $ 18.48 Forfeited (30,000 ) $ 18.48 Expired — $ — Outstanding at December 31, 2016 175,000 $ 18.48 1.2 $ 4,616 Granted — $ — Exercised (175,000 ) $ 18.48 Forfeited — $ — Expired — $ — Outstanding at December 31, 2017 — $ — N/A $ — Ending vested and expected to vest at December 31, — $ — N/A $ — Exercisable at December 31, 2017 — $ — N/A $ — Exercisable at December 31, 2016 175,000 $ 18.48 1.2 $ 4,616 Exercisable at December 31, 2015 164,589 $ 18.48 2.2 $ 2,241 December 31, 2017 , 2016 and 2015 is as follows: Weighted- Average Grant Date Fair Value Granted Shares Awarded Shares Shares Not Yet Awarded Outstanding at January 1, 2015 $ 28.19 6,659,047 1,060,890 5,598,157 Granted $ 31.74 481,166 164,646 316,520 Awarded $ — — — — Vested $ — — — — Forfeited $ 26.32 (863,241 ) (95,542 ) (767,699 ) Outstanding at December 31, 2015 $ 28.74 6,276,972 1,129,994 5,146,978 Granted $ 35.52 972,099 182,653 789,446 (1) Awarded $ 24.93 — 1,431,319 (1,431,319 ) Vested $ 27.31 (166,884 ) (166,884 ) — Forfeited $ 25.34 (954,131 ) (175,788 ) (778,343 ) Outstanding at December 31, 2016 $ 29.96 6,128,056 2,401,294 3,726,762 Granted $ 41.65 696,456 120,667 575,789 (2) Awarded $ 31.44 — 163,404 (163,404 ) Vested $ 25.22 (242,457 ) (242,457 ) — Forfeited $ 29.77 (171,060 ) (38,106 ) (132,954 ) Outstanding at December 31, 2017 $ 31.16 6,410,995 2,404,802 4,006,193 December 31, 2017 , 2016 and 2015 is as follows: Weighted- Average Grant Date Fair Value Granted Shares Awarded Shares Shares Not Yet Awarded Outstanding at January 1, 2015 $ 8.71 1,928,631 1,903,213 25,418 Granted $ — — — — Awarded $ — — — — Vested $ 5.55 (208,889 ) (208,889 ) — Forfeited $ 9.78 (117,528 ) (100,110 ) (17,418 ) Outstanding at December 31, 2015 $ 9.03 1,602,214 1,594,214 8,000 Granted $ — — — — Awarded $ — — 4,000 (4,000 ) Vested $ 6.39 (506,422 ) (506,422 ) — Forfeited $ 10.52 (92,517 ) (88,517 ) (4,000 ) Outstanding at December 31, 2016 $ 10.23 1,003,275 1,003,275 — Granted $ — — — — Awarded $ — — — — Vested $ 9.61 (138,801 ) (138,801 ) — Forfeited $ 10.47 (17,236 ) (17,236 ) — Outstanding at December 31, 2017 $ 10.32 847,238 847,238 —

Stock Based Compensation Stock

Stock Based Compensation Stock Options Outstanding (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block]	A summary of stock option activity for the years ended December 31, 2017 , 2016 and 2015 is as follows: Stock Options Shares Under Option Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term (in years) Aggregate Intrinsic Value (in thousands) Outstanding at January 1, 2015 470,356 $ 18.57 3.1 $ 5,087 Granted — $ — Exercised (151,767 ) $ 18.48 Forfeited (49,000 ) $ 19.36 Expired — $ — Outstanding at December 31, 2015 269,589 $ 18.48 2.2 $ 2,395 Granted — $ — Exercised (64,589 ) $ 18.48 Forfeited (30,000 ) $ 18.48 Expired — $ — Outstanding at December 31, 2016 175,000 $ 18.48 1.2 $ 4,616 Granted — $ — Exercised (175,000 ) $ 18.48 Forfeited — $ — Expired — $ — Outstanding at December 31, 2017 — $ — N/A $ — Ending vested and expected to vest at December 31, — $ — N/A $ — Exercisable at December 31, 2017 — $ — N/A $ — Exercisable at December 31, 2016 175,000 $ 18.48 1.2 $ 4,616 Exercisable at December 31, 2015 164,589 $ 18.48 2.2 $ 2,241 December 31, 2017 , 2016 and 2015 is as follows: Weighted- Average Grant Date Fair Value Granted Shares Awarded Shares Shares Not Yet Awarded Outstanding at January 1, 2015 $ 28.19 6,659,047 1,060,890 5,598,157 Granted $ 31.74 481,166 164,646 316,520 Awarded $ — — — — Vested $ — — — — Forfeited $ 26.32 (863,241 ) (95,542 ) (767,699 ) Outstanding at December 31, 2015 $ 28.74 6,276,972 1,129,994 5,146,978 Granted $ 35.52 972,099 182,653 789,446 (1) Awarded $ 24.93 — 1,431,319 (1,431,319 ) Vested $ 27.31 (166,884 ) (166,884 ) — Forfeited $ 25.34 (954,131 ) (175,788 ) (778,343 ) Outstanding at December 31, 2016 $ 29.96 6,128,056 2,401,294 3,726,762 Granted $ 41.65 696,456 120,667 575,789 (2) Awarded $ 31.44 — 163,404 (163,404 ) Vested $ 25.22 (242,457 ) (242,457 ) — Forfeited $ 29.77 (171,060 ) (38,106 ) (132,954 ) Outstanding at December 31, 2017 $ 31.16 6,410,995 2,404,802 4,006,193 December 31, 2017 , 2016 and 2015 is as follows: Weighted- Average Grant Date Fair Value Granted Shares Awarded Shares Shares Not Yet Awarded Outstanding at January 1, 2015 $ 8.71 1,928,631 1,903,213 25,418 Granted $ — — — — Awarded $ — — — — Vested $ 5.55 (208,889 ) (208,889 ) — Forfeited $ 9.78 (117,528 ) (100,110 ) (17,418 ) Outstanding at December 31, 2015 $ 9.03 1,602,214 1,594,214 8,000 Granted $ — — — — Awarded $ — — 4,000 (4,000 ) Vested $ 6.39 (506,422 ) (506,422 ) — Forfeited $ 10.52 (92,517 ) (88,517 ) (4,000 ) Outstanding at December 31, 2016 $ 10.23 1,003,275 1,003,275 — Granted $ — — — — Awarded $ — — — — Vested $ 9.61 (138,801 ) (138,801 ) — Forfeited $ 10.47 (17,236 ) (17,236 ) — Outstanding at December 31, 2017 $ 10.32 847,238 847,238 —

Supplemental Disclosures of C40

Supplemental Disclosures of Cash Flow Information and Non-Cash Financing and Investing Activities (Tables)	12 Months Ended
	Dec. 31, 2017
Supplemental Cash Flow Elements [Abstract]
Summary of Supplemental Disclosures of Cash Flow Information and Non-Cash Financing and Investing Activities	NOTE 12· Supplemental Disclosures of Cash Flow Information and Non-Cash Financing and Investing Activities Our Restricted Cash balance is comprised of funds held in separate premium trust accounts as required by state law or, in some cases, per agreement with our carrier partners. While these referenced funds are not restricted, they do represent premium payments from customers to be paid to insurance carriers and this change in classification should not be viewed as a source of operating cash. For the Year Ended December 31, (in thousands) 2017 2016 2015 Cash paid during the period for: Interest $ 36,172 $ 37,652 $ 37,542 Income taxes $ 152,024 $ 143,111 $ 132,874 Brown & Brown’s significant non-cash investing and financing activities are summarized as follows: For the Year Ended December 31, (in thousands) 2017 2016 2015 Other payables issued for purchased customer accounts $ 11,708 $ 10,664 $ 10,029 Estimated acquisition earn-out payables and related charges $ 6,921 $ 4,463 $ 36,899 Notes payable issued or assumed for purchased customer accounts $ — $ 492 $ — Notes received on the sale of fixed assets and customer accounts $ — $ 22 $ 7,755 The following is a reconciliation of cash and cash equivalents inclusive of restricted cash as of December 31, 2017 , 2016 and 2015 . Balance as of December 31, (in thousands) 2017 2016 2015 Table to reconcile cash and cash equivalents inclusive of restricted cash Cash and cash equivalents $ 573,383 $ 515,646 443,420 Restricted cash 250,705 265,637 229,753 Total cash and cash equivalents inclusive of restricted cash at the end of the period $ 824,088 $ 781,283 673,173

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block]	Brown & Brown leases facilities and certain items of office equipment under non-cancelable operating lease arrangements expiring on various dates through 2042. The facility leases generally contain renewal options and escalation clauses based upon increases in the lessors’ operating expenses and other charges. Brown & Brown anticipates that most of these leases will be renewed or replaced upon expiration. At December 31, 2017 , the aggregate future minimum lease payments under all non-cancelable lease agreements were as follows: (in thousands) 2018 $ 42,970 2019 39,005 2020 34,236 2021 27,715 2022 21,996 Thereafter 44,496 Total minimum future lease payments $ 210,418 Rental expense in 2017 , 2016 and 2015 for operating leases totaled $51.0 million , $49.3 million and $46.0 million

Quarterly Operating Results (Ta

Quarterly Operating Results (Tables)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Financial Information [Table Text Block]	Quarterly operating results for 2017 and 2016 were as follows: (in thousands, except per share data) First Quarter Second Quarter Third Quarter Fourth Quarter 2017 Total revenues $ 465,080 $ 466,305 $ 475,646 $ 474,316 Total expenses $ 354,113 $ 358,303 $ 351,227 $ 367,982 Income before income taxes $ 110,967 $ 108,002 $ 124,419 $ 106,334 Net income $ 70,110 $ 66,102 $ 75,913 $ 187,505 Net income per share: Basic $ 0.50 $ 0.47 $ 0.54 $ 1.35 Diluted $ 0.49 $ 0.46 $ 0.53 $ 1.32 (1) 2016 Total revenues $ 424,173 $ 446,518 $ 462,274 $ 433,664 Total expenses $ 321,624 $ 337,441 $ 345,302 $ 338,763 Income before income taxes $ 102,549 $ 109,077 $ 116,972 $ 94,901 Net income $ 62,070 $ 66,250 $ 71,545 $ 57,626 Net income per share: Basic $ 0.45 $ 0.47 $ 0.51 $ 0.41 Diluted $ 0.44 $ 0.47 $ 0.50 $ 0.41

Segment Information (Tables)

Segment Information (Tables)	12 Months Ended
	Dec. 31, 2017
Segment Reporting Information [Line Items]
Segment Information	Summarized financial information concerning the Company’s reportable segments is shown in the following table. The “Other” column includes any income and expenses not allocated to reportable segments and corporate-related items, including the intercompany interest expense charge to the reporting segment. For the year ended December 31, 2017 (in thousands) Retail National Programs Wholesale Brokerage Services Other Total Total revenues $ 943,460 $ 479,813 $ 271,737 $ 165,372 $ 20,965 $ 1,881,347 Investment income $ 8 $ 384 $ — $ 299 $ 935 $ 1,626 Amortization $ 42,164 $ 27,277 $ 11,456 $ 4,548 $ 1 $ 85,446 Depreciation $ 5,210 $ 6,325 $ 1,885 $ 1,600 $ 7,678 $ 22,698 Interest expense $ 31,133 $ 35,561 $ 6,263 $ 3,522 $ (38,163 ) $ 38,316 Income before income taxes $ 196,616 $ 109,961 $ 68,844 $ 30,498 $ 43,803 $ 449,722 Total assets $ 4,255,515 $ 3,267,486 $ 1,260,239 $ 399,240 $ (3,434,930 ) $ 5,747,550 Capital expenditures $ 4,494 $ 5,936 $ 1,836 $ 1,033 $ 10,893 $ 24,192 For the year ended December 31, 2016 (in thousands) Retail National Programs Wholesale Brokerage Services Other Total Total revenues $ 917,406 $ 448,516 $ 243,103 $ 156,365 $ 1,239 $ 1,766,629 Investment income $ 37 $ 628 $ 4 $ 283 $ 504 $ 1,456 Amortization $ 43,447 $ 27,920 $ 10,801 $ 4,485 $ 10 $ 86,663 Depreciation $ 6,191 $ 7,868 $ 1,975 $ 1,881 $ 3,088 $ 21,003 Interest expense $ 38,216 $ 45,738 $ 3,976 $ 4,950 $ (53,399 ) $ 39,481 Income before income taxes $ 188,001 $ 91,762 $ 62,623 $ 24,338 $ 56,775 $ 423,499 Total assets (1) $ 3,854,393 $ 2,711,378 $ 1,108,829 $ 371,645 $ (2,783,511 ) $ 5,262,734 Capital expenditures $ 5,951 $ 6,977 $ 1,301 $ 656 $ 2,880 $ 17,765 For the year ended December 31, 2015 (in thousands) Retail National Programs Wholesale Brokerage Services Other Total Total revenues $ 870,346 $ 428,734 $ 216,996 $ 145,365 $ (932 ) $ 1,660,509 Investment income $ 87 $ 210 $ 150 $ 42 $ 515 $ 1,004 Amortization $ 45,145 $ 28,479 $ 9,739 $ 4,019 $ 39 $ 87,421 Depreciation $ 6,558 $ 7,250 $ 2,142 $ 1,988 $ 2,952 $ 20,890 Interest expense $ 41,036 $ 55,705 $ 891 $ 5,970 $ (64,354 ) $ 39,248 Income before income taxes $ 181,938 $ 67,673 $ 64,708 $ 19,713 $ 68,527 $ 402,559 Total assets (1) $ 3,507,476 $ 2,503,537 $ 895,782 $ 285,459 $ (2,212,410 ) $ 4,979,844 Capital expenditures $ 6,797 $ 6,001 $ 3,084 $ 1,088 $ 1,405 $ 18,375

Losses and Loss Adjustment Re44

Losses and Loss Adjustment Reserve (Tables)	12 Months Ended
	Dec. 31, 2017
Reinsurance Disclosures [Abstract]
Effects of Reinsurance on Premiums Written and Earned	The effects of reinsurance on premiums written and earned at December 31 are as follows: 2017 2016 (in thousands) Written Earned Written Earned Direct premiums $ 604,623 $ 592,267 $ 591,142 $ 592,123 Assumed premiums — — — — Ceded premiums 604,610 592,254 591,124 592,105 Net premiums $ 13 $ 13 $ 18 $ 18

Summary of Significant Accoun45

Summary of Significant Accounting Policies Amortizable Intangible Assets (Details)	12 Months Ended
	Dec. 31, 2017
Minimum
Indefinite-lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	3 years
Maximum
Indefinite-lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	15 years

Summary of Significant Accoun46

Summary of Significant Accounting Policies Fair Value of Financial Instruments (Details) $ in Millions	Dec. 31, 2017USD ($)
Text Block [Abstract]
Long-term Debt, Fair Value	$ 598.9

Summary of Significant Accoun47

Summary of Significant Accounting Policies Fixed Assets (Details)	12 Months Ended
	Dec. 31, 2017
Minimum
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	3 years
Maximum
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	15 years

Summary of Significant Accoun48

Summary of Significant Accounting Policies Finite Lived Intangible Asset - Useful Life (Details)	12 Months Ended
	Dec. 31, 2017
Maximum
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	15 years
Minimum
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	3 years

Nature of Operations - Addition

Nature of Operations - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2017Segment
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of reportable segments	4

New Accounting Pronouncements (

New Accounting Pronouncements (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Jan. 01, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred Tax Assets Netted Against Deferred Tax Liabilities	$ 24.6
Scenario, Forecast [Member] | Minimum [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets		$ 70
Scenario, Forecast [Member] | Maximum [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets		$ 110

Net Income Per Share - Reconcil

Net Income Per Share - Reconciliation between Basic and Diluted Weighted Average Shares Outstanding (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share [Abstract]
Net income	$ 187,505	$ 75,913	$ 66,102	$ 70,110	$ 57,626	$ 71,545	$ 66,250	$ 62,070	$ 399,630	$ 257,491	$ 243,318
Net income attributable to unvested awarded performance stock									(9,746)	(6,705)	(5,695)
Net income attributable to common shares									$ 389,884	$ 250,786	$ 237,623
Weighted average number of common shares outstanding - basic (in shares)									139,697	139,779	141,113
Less unvested awarded performance stock included in weighted average number of common shares outstanding - basic (in shares)									(3,407)	(3,640)	(3,303)
Weighted average number of common shares outstanding for basic earnings per common share (in shares)									136,290	136,139	137,810
Dilutive effect of stock options (in shares)									2,503	1,665	2,302
Weighted average number of shares outstanding - diluted (in shares)									138,793	137,804	140,112
Basic (in dollars per share)	$ 0.0135	$ 0.0054	$ 0.0047	$ 0.0050	$ 0.0041	$ 0.0051	$ 0.0047	$ 0.0045	$ 2.86	$ 1.84	$ 1.72
Diluted (in dollars per share)	$ 0.0132	$ 0.0053	$ 0.0046	$ 0.0049	$ 0.0041	$ 0.0050	$ 0.0047	$ 0.0044	$ 2.81	$ 1.82	$ 1.70

Business Combinations - Additio

Business Combinations - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2017USD ($)acquisition	Dec. 31, 2016USD ($)acquisition	Dec. 31, 2015USD ($)acquisitioncustomer_account	Dec. 31, 2014USD ($)
Business Acquisition [Line Items]
Maximum Future Contingency payments Acquisitions	$ 88,400,000
Number of acquisitions | acquisition	11	8
Aggregate purchase price of acquisitions	$ 1,500,000	$ 917,497	$ 503,442
Payments to Acquire Businesses, Gross	41,471,000	124,716,000	136,000,000
Goodwill assigned	42,172,000	93,376,000	136,381,000
Goodwill currently deductible for income tax purposes	35,300,000	88,900,000	91,100,000
Goodwill currently non-deductible for income tax purposes			8,400,000
Goodwill related to the recorded earn-out payables	6,900,000	4,500,000	36,900,000
Total revenues related to acquisitions	7,800,000	34,200,000	28,200,000
Income before income taxes related to acquisitions	2,400,000	4,300,000	1,500,000
Estimated acquisition earn-out payables	36,175,000	63,821,000	78,387,000	$ 75,283,000
Other Payable	11,708,000	10,664,000	10,028,000
Business Acquisitions Contingent Consideration At Fair Value	6,921,000	4,462,000	36,899,000
Net Assets Acquired	60,100,000	140,334,000	182,927,000
Maximum Potential Earn- Out Payable	27,451,000	16,285,000	73,074,000
Accounts payable
Business Acquisition [Line Items]
Estimated acquisition earn-out payables	$ 25,100,000	$ 31,800,000	$ 25,300,000
Purchased customer accounts
Business Acquisition [Line Items]
Weighted average life (years)	15 years	15 years	15 years
Non-compete agreements
Business Acquisition [Line Items]
Weighted average life (years)	5 years	5 years	5 years
National Programs
Business Acquisition [Line Items]
Goodwill assigned	$ 7,200,000	$ 57,900,000	$ 18,000,000
Wholesale Brokerage [Member]
Business Acquisition [Line Items]
Goodwill assigned	1,200,000	(1,200)	4,600,000
Services [Member]
Business Acquisition [Line Items]
Goodwill assigned	700,000	22,400,000
Other non-current liability
Business Acquisition [Line Items]
Estimated acquisition earn-out payables	$ 11,100,000	32,000,000	$ 53,100,000
Social Security Advocates for the Disabled LLC [Member]
Business Acquisition [Line Items]
Goodwill assigned		22,352,000
Net Assets Acquired		$ 33,989,000
Social Security Advocates for the Disabled LLC [Member] | Services [Member]
Business Acquisition [Line Items]
Effective Date of Acquisition		Feb. 1, 2016
Payments to Acquire Businesses, Gross		$ 32,526,000
Other Payable		0
Business Acquisitions Contingent Consideration At Fair Value		971,000
Net Assets Acquired		33,989,000
Maximum Potential Earn- Out Payable		3,500,000
Morstan General Agency, Inc [Member]
Business Acquisition [Line Items]
Goodwill assigned		51,454,000
Net Assets Acquired		$ 79,341,000
Morstan General Agency, Inc [Member] | Wholesale Brokerage [Member]
Business Acquisition [Line Items]
Effective Date of Acquisition		Jun. 1, 2016
Payments to Acquire Businesses, Gross		$ 66,050,000
Other Payable		10,200,000
Business Acquisitions Contingent Consideration At Fair Value		3,091,000
Net Assets Acquired		79,341,000
Maximum Potential Earn- Out Payable		$ 5,000,000
Asset Acquisitions [Member]
Business Acquisition [Line Items]
Number of acquisitions | acquisition	11	7	13
Book of Business Purchases [Member]
Business Acquisition [Line Items]
Number of acquisitions	1	3	4
Other Acquisitions [Member]
Business Acquisition [Line Items]
Goodwill assigned			$ 21,040,000
Net Assets Acquired			17,605,000
Other Acquisitions [Member] | Various
Business Acquisition [Line Items]
Payments to Acquire Businesses, Gross	$ 41,471,000	$ 26,140,000	12,926,000
Other Payable	11,708,000	464,000	95,000
Business Acquisitions Contingent Consideration At Fair Value	6,921,000	400,000	4,584,000
Net Assets Acquired	60,100,000	27,004,000	17,605,000
Maximum Potential Earn- Out Payable	$ 27,451,000	$ 7,785,000	$ 8,212,000

Business Combinations - Acquisi

Business Combinations - Acquisitions Accounted for Business Combinations (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Business Combination, Separately Recognized Transactions [Line Items]
Cash Paid	$ 41,471	$ 124,716	$ 136,000
Other Payable	11,708	10,664	10,028
Recorded Earn-Out Payable	6,921	4,462	36,899
Net Assets Acquired	60,100	140,334	182,927
Maximum Potential Earn- Out Payable	27,451	16,285	73,074
Liberty Insurance Brokers, Inc. and Affiliates [Member]
Business Combination, Separately Recognized Transactions [Line Items]
Net Assets Acquired			$ 14,981
Liberty Insurance Brokers, Inc. and Affiliates [Member] | Retail
Business Combination, Separately Recognized Transactions [Line Items]
Effective Date of Acquisition			Feb. 1, 2015
Cash Paid			$ 12,000
Other Payable			0
Recorded Earn-Out Payable			2,981
Net Assets Acquired			14,981
Maximum Potential Earn- Out Payable			3,750
Spain Agency, Inc. (Spain)
Business Combination, Separately Recognized Transactions [Line Items]
Net Assets Acquired			$ 23,323
Spain Agency, Inc. (Spain) | Retail
Business Combination, Separately Recognized Transactions [Line Items]
Effective Date of Acquisition			Mar. 1, 2015
Cash Paid			$ 20,706
Other Payable			0
Recorded Earn-Out Payable			2,617
Net Assets Acquired			23,323
Maximum Potential Earn- Out Payable			9,162
Bellingham Underwriters, Inc. [Member]
Business Combination, Separately Recognized Transactions [Line Items]
Net Assets Acquired			$ 12,829
Bellingham Underwriters, Inc. [Member] | National Programs
Business Combination, Separately Recognized Transactions [Line Items]
Effective Date of Acquisition			May 1, 2015
Bellingham Underwriters, Inc. [Member] | National Programs Divisions [Member]
Business Combination, Separately Recognized Transactions [Line Items]
Cash Paid			$ 9,007
Other Payable			500
Recorded Earn-Out Payable			3,322
Net Assets Acquired			12,829
Maximum Potential Earn- Out Payable			4,400
Fitness Insurance, LLC [Member]
Business Combination, Separately Recognized Transactions [Line Items]
Net Assets Acquired			$ 11,834
Fitness Insurance, LLC [Member] | Retail
Business Combination, Separately Recognized Transactions [Line Items]
Effective Date of Acquisition			Jun. 1, 2015
Cash Paid			$ 9,455
Other Payable			0
Recorded Earn-Out Payable			2,379
Net Assets Acquired			11,834
Maximum Potential Earn- Out Payable			3,500
Other
Business Combination, Separately Recognized Transactions [Line Items]
Net Assets Acquired			$ 63,587
Other | Retail
Business Combination, Separately Recognized Transactions [Line Items]
Effective Date of Acquisition			Jun. 1, 2015
Cash Paid			$ 49,600
Other Payable			400
Recorded Earn-Out Payable			13,587
Net Assets Acquired			63,587
Maximum Potential Earn- Out Payable			26,000
Bentrust Financial, Inc. [Member]
Business Combination, Separately Recognized Transactions [Line Items]
Net Assets Acquired			$ 10,852
Bentrust Financial, Inc. [Member] | Retail
Business Combination, Separately Recognized Transactions [Line Items]
Effective Date of Acquisition			Dec. 1, 2015
Cash Paid			$ 10,142
Other Payable			391
Recorded Earn-Out Payable			319
Net Assets Acquired			10,852
Maximum Potential Earn- Out Payable			2,200
MBA Insurance Agency of Arizona, Inc. [Member]
Business Combination, Separately Recognized Transactions [Line Items]
Net Assets Acquired			$ 14,573
MBA Insurance Agency of Arizona, Inc. [Member] | Retail
Business Combination, Separately Recognized Transactions [Line Items]
Effective Date of Acquisition			Dec. 1, 2015
Cash Paid			$ 68
Other Payable			8,442
Recorded Earn-Out Payable			6,063
Net Assets Acquired			14,573
Maximum Potential Earn- Out Payable			9,500
Smith Insurance, Inc. [Member]
Business Combination, Separately Recognized Transactions [Line Items]
Net Assets Acquired			$ 13,343
Smith Insurance, Inc. [Member] | Retail
Business Combination, Separately Recognized Transactions [Line Items]
Effective Date of Acquisition			Dec. 1, 2015
Cash Paid			$ 12,096
Other Payable			200
Recorded Earn-Out Payable			1,047
Net Assets Acquired			13,343
Maximum Potential Earn- Out Payable			6,350
Other Acquisitions [Member]
Business Combination, Separately Recognized Transactions [Line Items]
Net Assets Acquired			17,605
Other Acquisitions [Member] | Various
Business Combination, Separately Recognized Transactions [Line Items]
Cash Paid	41,471	26,140	12,926
Other Payable	11,708	464	95
Recorded Earn-Out Payable	6,921	400	4,584
Net Assets Acquired	60,100	27,004	17,605
Maximum Potential Earn- Out Payable	$ 27,451	7,785	$ 8,212
Various
Business Combination, Separately Recognized Transactions [Line Items]
Net Assets Acquired		$ 27,004
Two Thousand Fifteen Acquisitions [Member]
Business Combination, Separately Recognized Transactions [Line Items]
Business Acquisition, Pro Forma Income (Loss) from Continuing Operations before Changes in Accounting and Extraordinary Items, Net of Tax, Per Share, Diluted			$ 1.73
Pro Forma Weighted Average Shares Outstanding, Diluted			140,112

Business Combinations - Estimat

Business Combinations - Estimated Fair Values of Aggregate Assets and Liabilities Acquired (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Fair Value Of Assets And Liabilities Statement [Line Items]
Other Payable	$ 11,708,000	$ 10,664,000	$ 10,028,000
Payments to Acquire Businesses, Gross	41,471,000	124,716,000	136,000,000
Recorded Earn-Out Payable	6,921,000	4,462,000	36,899,000
Business Acquisition Purchase Price Allocation Current Assets Prepaid Expenses And Other Assets		2,094,000
Business Acquisition Purchase Price Allocation Current Assets Prepaid Expenses And Other Assets	601,000	5,079,000	3,640,000
Fixed assets	69,000	684,000	374,000
Goodwill	42,172,000	93,376,000	136,381,000
Purchased customer accounts	18,738,000	50,625,000	53,392,000
Non-compete agreements	721,000	228,000	328,000
Business Acquisitions Purchase Price Allocation Other Noncurrent Assets		20,000	14,000
Total assets acquired	62,301,000	152,106,000	194,129,000
Other current liabilities	(1,512,000)	(8,542,000)	(12,213,000)
Deferred Tax Liabilities, Net	(689,000)	(3,230,000)
Deferred Tax Assets, Net			2,576,000
Other liabilities			(1,565,000)
Total liabilities assumed	(2,201,000)	(11,772,000)	(11,202,000)
Net assets acquired	60,100,000	140,334,000	182,927,000
Maximum Potential Earn- Out Payable	27,451,000	16,285,000	73,074,000
Social Security Advocates for the Disabled LLC [Member]
Fair Value Of Assets And Liabilities Statement [Line Items]
Business Acquisition Purchase Price Allocation Current Assets Prepaid Expenses And Other Assets		2,094,000
Business Acquisition Purchase Price Allocation Current Assets Prepaid Expenses And Other Assets		1,042,000
Fixed assets		307,000
Goodwill		22,352,000
Purchased customer accounts		13,069,000
Non-compete agreements		72,000
Business Acquisitions Purchase Price Allocation Other Noncurrent Assets		0
Total assets acquired		38,936,000
Other current liabilities		(1,717,000)
Deferred Tax Liabilities, Net		(3,230,000)
Total liabilities assumed		(4,947,000)
Net assets acquired		33,989,000
Various [Member]
Fair Value Of Assets And Liabilities Statement [Line Items]
Business Acquisition Purchase Price Allocation Current Assets Prepaid Expenses And Other Assets		0
Business Acquisition Purchase Price Allocation Current Assets Prepaid Expenses And Other Assets		1,555,000
Fixed assets		77,000
Goodwill		19,570,000
Purchased customer accounts		11,075,000
Non-compete agreements		117,000
Business Acquisitions Purchase Price Allocation Other Noncurrent Assets		20,000
Total assets acquired		32,414,000
Other current liabilities		(5,410,000)
Deferred Tax Liabilities, Net		0
Total liabilities assumed		(5,410,000)
Net assets acquired		27,004,000
Morstan General Agency, Inc [Member]
Fair Value Of Assets And Liabilities Statement [Line Items]
Business Acquisition Purchase Price Allocation Current Assets Prepaid Expenses And Other Assets		0
Business Acquisition Purchase Price Allocation Current Assets Prepaid Expenses And Other Assets		2,482,000
Fixed assets		300,000
Goodwill		51,454,000
Purchased customer accounts		26,481,000
Non-compete agreements		39,000
Business Acquisitions Purchase Price Allocation Other Noncurrent Assets		0
Total assets acquired		80,756,000
Other current liabilities		(1,415,000)
Deferred Tax Liabilities, Net		0
Total liabilities assumed		(1,415,000)
Net assets acquired		79,341,000
Spain Agency, Inc. (Spain)
Fair Value Of Assets And Liabilities Statement [Line Items]
Business Acquisition Purchase Price Allocation Current Assets Prepaid Expenses And Other Assets			324,000
Fixed assets			50,000
Goodwill			15,748,000
Purchased customer accounts			7,430,000
Non-compete agreements			21,000
Business Acquisitions Purchase Price Allocation Other Noncurrent Assets			0
Total assets acquired			23,573,000
Other current liabilities			(250,000)
Deferred Tax Liabilities, Net			0
Other liabilities			0
Total liabilities assumed			(250,000)
Net assets acquired			23,323,000
Bellingham Underwriters, Inc. [Member]
Fair Value Of Assets And Liabilities Statement [Line Items]
Business Acquisition Purchase Price Allocation Current Assets Prepaid Expenses And Other Assets			0
Fixed assets			25,000
Goodwill			9,608,000
Purchased customer accounts			3,223,000
Non-compete agreements			21,000
Business Acquisitions Purchase Price Allocation Other Noncurrent Assets			0
Total assets acquired			12,877,000
Other current liabilities			(48,000)
Deferred Tax Liabilities, Net			0
Other liabilities			0
Total liabilities assumed			(48,000)
Net assets acquired			12,829,000
Fitness Insurance, LLC [Member]
Fair Value Of Assets And Liabilities Statement [Line Items]
Business Acquisition Purchase Price Allocation Current Assets Prepaid Expenses And Other Assets			9,000
Fixed assets			17,000
Goodwill			8,105,000
Purchased customer accounts			3,715,000
Non-compete agreements			0
Business Acquisitions Purchase Price Allocation Other Noncurrent Assets			0
Total assets acquired			11,846,000
Other current liabilities			(12,000)
Deferred Tax Liabilities, Net			0
Other liabilities			0
Total liabilities assumed			(12,000)
Net assets acquired			11,834,000
Other
Fair Value Of Assets And Liabilities Statement [Line Items]
Business Acquisition Purchase Price Allocation Current Assets Prepaid Expenses And Other Assets			652,000
Fixed assets			41,000
Goodwill			39,859,000
Purchased customer accounts			23,000,000
Non-compete agreements			21,000
Business Acquisitions Purchase Price Allocation Other Noncurrent Assets			14,000
Total assets acquired			63,587,000
Other current liabilities			0
Deferred Tax Liabilities, Net			0
Other liabilities			0
Total liabilities assumed			0
Net assets acquired			63,587,000
Bentrust Financial, Inc. [Member]
Fair Value Of Assets And Liabilities Statement [Line Items]
Business Acquisition Purchase Price Allocation Current Assets Prepaid Expenses And Other Assets			0
Fixed assets			36,000
Goodwill			8,166,000
Purchased customer accounts			2,789,000
Non-compete agreements			43,000
Business Acquisitions Purchase Price Allocation Other Noncurrent Assets			0
Total assets acquired			11,034,000
Other current liabilities			(182,000)
Deferred Tax Liabilities, Net			0
Other liabilities			0
Total liabilities assumed			(182,000)
Net assets acquired			10,852,000
MBA Insurance Agency of Arizona, Inc. [Member]
Fair Value Of Assets And Liabilities Statement [Line Items]
Business Acquisition Purchase Price Allocation Current Assets Prepaid Expenses And Other Assets			0
Fixed assets			33,000
Goodwill			13,471,000
Purchased customer accounts			7,338,000
Non-compete agreements			11,000
Business Acquisitions Purchase Price Allocation Other Noncurrent Assets			0
Total assets acquired			20,853,000
Other current liabilities			(6,280,000)
Deferred Tax Liabilities, Net			0
Other liabilities			0
Total liabilities assumed			(6,280,000)
Net assets acquired			14,573,000
Smith Insurance, Inc. [Member]
Fair Value Of Assets And Liabilities Statement [Line Items]
Business Acquisition Purchase Price Allocation Current Assets Prepaid Expenses And Other Assets			0
Fixed assets			73,000
Goodwill			10,374,000
Purchased customer accounts			3,526,000
Non-compete agreements			31,000
Business Acquisitions Purchase Price Allocation Other Noncurrent Assets			0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Prepaid Expense and Other Assets			14,004,000
Other current liabilities			(504,000)
Deferred Tax Liabilities, Net			0
Other liabilities			(157,000)
Total liabilities assumed			(661,000)
Net assets acquired			13,343,000
Other Acquisitions [Member]
Fair Value Of Assets And Liabilities Statement [Line Items]
Business Acquisition Purchase Price Allocation Current Assets Prepaid Expenses And Other Assets			169,000
Fixed assets			59,000
Goodwill			21,040,000
Purchased customer accounts			(2,135,000)
Non-compete agreements			156,000
Business Acquisitions Purchase Price Allocation Other Noncurrent Assets			0
Total assets acquired			19,289,000
Other current liabilities			(4,895,000)
Deferred Tax Assets, Net			2,576,000
Other liabilities			635,000
Total liabilities assumed			(1,684,000)
Net assets acquired			17,605,000
Liberty Insurance Brokers, Inc. and Affiliates [Member]
Fair Value Of Assets And Liabilities Statement [Line Items]
Business Acquisition Purchase Price Allocation Current Assets Prepaid Expenses And Other Assets			2,486,000
Fixed assets			40,000
Goodwill			10,010,000
Purchased customer accounts			4,506,000
Non-compete agreements			24,000
Business Acquisitions Purchase Price Allocation Other Noncurrent Assets			0
Total assets acquired			17,066,000
Other current liabilities			(42,000)
Deferred Tax Liabilities, Net			0
Other liabilities			(2,043,000)
Total liabilities assumed			(2,085,000)
Net assets acquired			14,981,000
Services
Fair Value Of Assets And Liabilities Statement [Line Items]
Goodwill	700,000	$ 22,400,000
Services | Social Security Advocates for the Disabled LLC [Member]
Fair Value Of Assets And Liabilities Statement [Line Items]
Effective Date of Acquisition		Feb. 1, 2016
Other Payable		$ 0
Payments to Acquire Businesses, Gross		32,526,000
Recorded Earn-Out Payable		971,000
Net assets acquired		33,989,000
Maximum Potential Earn- Out Payable		3,500,000
Retail
Fair Value Of Assets And Liabilities Statement [Line Items]
Goodwill	33,100,000	13,100,000	$ 113,800,000
Retail | Spain Agency, Inc. (Spain)
Fair Value Of Assets And Liabilities Statement [Line Items]
Effective Date of Acquisition			Mar. 1, 2015
Other Payable			$ 0
Payments to Acquire Businesses, Gross			20,706,000
Recorded Earn-Out Payable			2,617,000
Net assets acquired			23,323,000
Maximum Potential Earn- Out Payable			$ 9,162,000
Retail | Fitness Insurance, LLC [Member]
Fair Value Of Assets And Liabilities Statement [Line Items]
Effective Date of Acquisition			Jun. 1, 2015
Other Payable			$ 0
Payments to Acquire Businesses, Gross			9,455,000
Recorded Earn-Out Payable			2,379,000
Net assets acquired			11,834,000
Maximum Potential Earn- Out Payable			$ 3,500,000
Retail | Other
Fair Value Of Assets And Liabilities Statement [Line Items]
Effective Date of Acquisition			Jun. 1, 2015
Other Payable			$ 400,000
Payments to Acquire Businesses, Gross			49,600,000
Recorded Earn-Out Payable			13,587,000
Net assets acquired			63,587,000
Maximum Potential Earn- Out Payable			$ 26,000,000
Retail | Bentrust Financial, Inc. [Member]
Fair Value Of Assets And Liabilities Statement [Line Items]
Effective Date of Acquisition			Dec. 1, 2015
Other Payable			$ 391,000
Payments to Acquire Businesses, Gross			10,142,000
Recorded Earn-Out Payable			319,000
Net assets acquired			10,852,000
Maximum Potential Earn- Out Payable			$ 2,200,000
Retail | MBA Insurance Agency of Arizona, Inc. [Member]
Fair Value Of Assets And Liabilities Statement [Line Items]
Effective Date of Acquisition			Dec. 1, 2015
Other Payable			$ 8,442,000
Payments to Acquire Businesses, Gross			68,000
Recorded Earn-Out Payable			6,063,000
Net assets acquired			14,573,000
Maximum Potential Earn- Out Payable			$ 9,500,000
Retail | Smith Insurance, Inc. [Member]
Fair Value Of Assets And Liabilities Statement [Line Items]
Effective Date of Acquisition			Dec. 1, 2015
Other Payable			$ 200,000
Payments to Acquire Businesses, Gross			12,096,000
Recorded Earn-Out Payable			1,047,000
Net assets acquired			13,343,000
Maximum Potential Earn- Out Payable			$ 6,350,000
Retail | Liberty Insurance Brokers, Inc. and Affiliates [Member]
Fair Value Of Assets And Liabilities Statement [Line Items]
Effective Date of Acquisition			Feb. 1, 2015
Other Payable			$ 0
Payments to Acquire Businesses, Gross			12,000,000
Recorded Earn-Out Payable			2,981,000
Net assets acquired			14,981,000
Maximum Potential Earn- Out Payable			3,750,000
National Programs
Fair Value Of Assets And Liabilities Statement [Line Items]
Goodwill	7,200,000	57,900,000	$ 18,000,000
National Programs | Bellingham Underwriters, Inc. [Member]
Fair Value Of Assets And Liabilities Statement [Line Items]
Effective Date of Acquisition			May 1, 2015
Wholesale Brokerage
Fair Value Of Assets And Liabilities Statement [Line Items]
Goodwill	$ 1,200,000	$ (1,200)	$ 4,600,000
Wholesale Brokerage | Morstan General Agency, Inc [Member]
Fair Value Of Assets And Liabilities Statement [Line Items]
Effective Date of Acquisition		Jun. 1, 2016
Other Payable		$ 10,200,000
Payments to Acquire Businesses, Gross		66,050,000
Recorded Earn-Out Payable		3,091,000
Net assets acquired		79,341,000
Maximum Potential Earn- Out Payable		$ 5,000,000

Business Combinations - Results

Business Combinations - Results of Operations (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual	$ 7,800	$ 34,200	$ 28,200
Business Combination Pro Forma Information Income Loss Before Income Taxes Of Acquiree Since Acquisition Date Actual	2,400	4,300	1,500
Two Thousand Seventeen Acquisition [Member] [Domain]
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Total revenues	1,891,701	1,784,776
Income before income taxes	453,397	429,490
Net income	$ 401,908	$ 261,133
Net income per share:
Basic (in dollars per share)	$ 2.88	$ 1.87
Business Acquisition, Pro Forma Income (Loss) from Continuing Operations before Changes in Accounting and Extraordinary Items, Net of Tax, Per Share, Diluted	$ 2.83	$ 1.85
Weighted Average Basic Shares Outstanding, Pro Forma	136,290	136,139
Weighted average number of shares outstanding:
Pro Forma Weighted Average Shares Outstanding, Diluted	138,793	137,804
Two Thousand Fifteen Acquisitions [Member]
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Total revenues			1,688,297
Income before income taxes			411,497
Net income			$ 248,720
Net income per share:
Basic (in dollars per share)			$ 1.76
Business Acquisition, Pro Forma Income (Loss) from Continuing Operations before Changes in Accounting and Extraordinary Items, Net of Tax, Per Share, Diluted			$ 1.73
Weighted Average Basic Shares Outstanding, Pro Forma			137,810
Weighted average number of shares outstanding:
Pro Forma Weighted Average Shares Outstanding, Diluted			140,112

Business Combinations - Addit56

Business Combinations - Additions, Payments, and Net Changes, as well as Interest Expense Accretion on Estimated Acquisition Earn-Out Payables (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Business Acquisition [Line Items]
Business Acquisition Cost- Note Payable		$ 492
Beginning balance	$ 63,821	78,387	$ 75,283
Additions to estimated acquisition earn-out payables	6,920	4,462	36,899
Payments for estimated acquisition earn-out payables	43,766	28,213	36,798
Subtotal	26,975	54,636	75,384
Net change in earnings from estimated acquisition earn-out payables:
Change in fair value on estimated acquisition earn-out payables	(6,874)	(6,338)	(13)
Interest expense accretion	2,326	2,847	2,990
Net change in earnings from estimated acquisition earn-out payables	9,200	9,185	3,003
Ending balance	$ 36,175	63,821	$ 78,387
Services | Social Security Advocates for the Disabled LLC [Member]
Business Acquisition [Line Items]
Business Acquisition Cost- Note Payable		492
Wholesale Brokerage [Member] | Morstan General Agency, Inc [Member]
Business Acquisition [Line Items]
Business Acquisition Cost- Note Payable		0
Various [Member] | Other Acquisitions [Member]
Business Acquisition [Line Items]
Business Acquisition Cost- Note Payable		$ 0

Business Combinations Business

Business Combinations Business Acquisitions - Pro-forma Table (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Two Thousand Sixteen Acquisition [Member]
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Weighted Average Basic Shares Outstanding, Pro Forma		136,139	137,810
Business Acquisition, Pro Forma Revenue		$ 1,789,790	$ 1,716,592
Business Acquisition, Pro Forma Income (Loss) from Continuing Operations before Changes in Accounting and Extraordinary Items, Net of Tax		428,194	414,911
Business Acquisition, Pro Forma Net Income (Loss)		$ 260,346	$ 250,783
Business Acquisition, Pro Forma Income (Loss) from Continuing Operations before Changes in Accounting and Extraordinary Items, Net of Tax, Per Share, Basic		$ 1.86	$ 1.78
Business Acquisition, Pro Forma Income (Loss) from Continuing Operations before Changes in Accounting and Extraordinary Items, Net of Tax, Per Share, Diluted		$ 1.84	$ 1.75
Pro Forma Weighted Average Shares Outstanding, Diluted		137,804	140,112
Two Thousand Fifteen Acquisitions [Member]
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Weighted Average Basic Shares Outstanding, Pro Forma			137,810
Business Acquisition, Pro Forma Revenue			$ 1,688,297
Business Acquisition, Pro Forma Income (Loss) from Continuing Operations before Changes in Accounting and Extraordinary Items, Net of Tax			411,497
Business Acquisition, Pro Forma Net Income (Loss)			$ 248,720
Business Acquisition, Pro Forma Income (Loss) from Continuing Operations before Changes in Accounting and Extraordinary Items, Net of Tax, Per Share, Basic			$ 1.76
Business Acquisition, Pro Forma Income (Loss) from Continuing Operations before Changes in Accounting and Extraordinary Items, Net of Tax, Per Share, Diluted			$ 1.73
Pro Forma Weighted Average Shares Outstanding, Diluted			140,112
Two Thousand Seventeen Acquisition [Member] [Domain]
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Weighted Average Basic Shares Outstanding, Pro Forma	136,290	136,139
Business Acquisition, Pro Forma Revenue	$ 1,891,701	$ 1,784,776
Business Acquisition, Pro Forma Income (Loss) from Continuing Operations before Changes in Accounting and Extraordinary Items, Net of Tax	453,397	429,490
Business Acquisition, Pro Forma Net Income (Loss)	$ 401,908	$ 261,133
Business Acquisition, Pro Forma Income (Loss) from Continuing Operations before Changes in Accounting and Extraordinary Items, Net of Tax, Per Share, Basic	$ 2.88	$ 1.87
Business Acquisition, Pro Forma Income (Loss) from Continuing Operations before Changes in Accounting and Extraordinary Items, Net of Tax, Per Share, Diluted	$ 2.83	$ 1.85
Pro Forma Weighted Average Shares Outstanding, Diluted	138,793	137,804

Goodwill - Changes in Carrying

Goodwill - Changes in Carrying Value of Goodwill by Operating Segment (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Goodwill [Roll Forward]
Beginning balance	$ 2,675,402	$ 2,586,683
Goodwill of acquired businesses	42,172	93,376
Goodwill disposed of relating to sales of businesses	(1,495)	(4,657)
Ending balance	2,716,079	2,675,402
Retail
Goodwill [Roll Forward]
Beginning balance	1,354,667	1,345,636
Goodwill of acquired businesses	33,076	13,117
Goodwill disposed of relating to sales of businesses	(1,495)	(4,657)
Ending balance	1,386,248	1,354,667
National Programs
Goodwill [Roll Forward]
Beginning balance	901,294	901,866
Goodwill of acquired businesses	7,178	(1)
Goodwill disposed of relating to sales of businesses	0	0
Ending balance	908,472	901,294
Wholesale Brokerage
Goodwill [Roll Forward]
Beginning balance	284,869	226,961
Goodwill of acquired businesses	1,229	57,908
Goodwill disposed of relating to sales of businesses	0	0
Ending balance	286,098	284,869
Services
Goodwill [Roll Forward]
Beginning balance	134,572	112,220
Goodwill of acquired businesses	689	22,352
Goodwill disposed of relating to sales of businesses	0	0
Ending balance	$ 135,261	$ 134,572

Amortizable Intangible Assets -

Amortizable Intangible Assets - Amortizable Intangible Assets (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 1,494,561	$ 1,477,348
Accumulated Amortization	(853,556)	(769,894)
Net Carrying Value	641,005	707,454
Purchased customer accounts
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	1,464,274	1,447,680
Accumulated Amortization	(824,584)	(741,770)
Net Carrying Value	$ 639,690	$ 705,910
Weighted Average Life (Years)	15 years	15 years
Non-compete agreements
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 30,287	$ 29,668
Accumulated Amortization	(28,972)	(28,124)
Net Carrying Value	$ 1,315	$ 1,544
Weighted Average Life (Years)	6 years 9 months 18 days	6 years 9 months 18 days

Amortizable Intangible Assets60

Amortizable Intangible Assets - Additional Information (Detail) $ in Millions	Dec. 31, 2017USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization expense estimated, year one (2015)	$ 81
Amortization expense estimated, year two (2016)	76.5
Amortization expense estimated, year three (2017)	69.1
Amortization expense estimated, year four (2018)	65.9
Amortization expense estimated, year five (2019)	$ 61.4

Investments - Schedule of Inves

Investments - Schedule of Investments in Fixed Maturity Securities (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Proceeds from Sale, Maturity and Collection of Investments	$ 9,644	$ 18,890	$ 21,928
Cost	31,042	28,638
Gross Unrealized Gains	12	24
Gross Unrealized Losses	(206)	(60)
Fair Value	30,848	$ 28,602
Short-term Debt [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	$ 16,900

Investments - Summary of Unreal

Investments - Summary of Unrealized Loss Position (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	$ 31,042	$ 28,638
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	12	24
Fair Value, Less than 12 Months	18,319	15,664
Unrealized Losses, Less than 12 Months	(157)	(60)
Fair Value, 12 Months or More	11,845	0
Unrealized Losses, 12 Months or More	(49)	0
Fair Value	30,164	15,664
Unrealized Losses	(206)	(60)
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(206)	(60)
Available-for-sale Securities	30,848	28,602
U.S. Treasury securities, obligations of U.S. Government agencies and Municipals
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	29,970	26,280
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	0	11
Fair Value, Less than 12 Months	17,919	14,663
Unrealized Losses, Less than 12 Months	(157)	(59)
Fair Value, 12 Months or More	11,845	0
Unrealized Losses, 12 Months or More	(49)	0
Fair Value	29,764	14,663
Unrealized Losses	(206)	(59)
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(206)	(59)
Available-for-sale Securities	29,764	26,232
Corporate debt
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	1,072	2,358
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	12	13
Fair Value, Less than 12 Months	400	1,001
Unrealized Losses, Less than 12 Months	0	(1)
Fair Value, 12 Months or More	0	0
Unrealized Losses, 12 Months or More	0	0
Fair Value	400	1,001
Unrealized Losses	0	(1)
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	0	(1)
Available-for-sale Securities	$ 1,084	$ 2,370

Investments - Additional Inform

Investments - Additional Information (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)Securities	Dec. 31, 2016USD ($)Securities
Schedule of Available-for-sale Securities [Line Items]
Short-term Investments	$ 24,965	$ 15,048
Number of securities in unrealized loss position | Securities	27	20
Proceeds from sale of investment in fixed maturity securities	$ 5,800	$ 6,000
Money Market Funds, at Carrying Value		$ 9,100
Investments on deposit with the state insurance department	4,100
Time Deposits	$ 8,100

Investments - Amortized Cost an

Investments - Amortized Cost and Fair Value of Fixed Maturity Securities by Contractual Maturity (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Amortized Cost
Due in one year or less	$ 16,934	$ 5,551
Due after one year through five years	13,876	22,757
Due after five years through ten years	232	330
Amortized Cost, Total	31,042	28,638
Fair Value
Due in one year or less	16,899	5,554
Due after one year through five years	13,708	22,708
Due after five years through ten years	241	340
Fair Value, Total	$ 30,848	$ 28,602

Fixed Assets (Details)

Fixed Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Depreciation	$ 22,698	$ 21,003	$ 20,890
Property, Plant and Equipment, Gross	233,908	214,335
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	(156,822)	(138,528)
Property, Plant and Equipment, Net	77,086	75,807
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	190,784	177,823
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	35,481	33,137
Land, Buildings and Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 7,643	$ 3,375

Long-Term Debt - Long-Term Debt

Long-Term Debt - Long-Term Debt Instrument (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 22, 2016
Debt Instrument [Line Items]
Long-term Debt, Maturities, Repayments of Principal in Year Five	$ 255,000
Document Period End Date	Dec. 31, 2017
Total current portion of long-term debt	$ 120,000	$ 55,500
Total notes	498,943	598,785
Long-term credit agreements	365,000	426,250
Debt Issuance Costs, Net	(7,802)	(6,663)
Total long-term debt	856,141	1,018,372
Current portion of long-term debt	120,000	55,500
Total debt	976,141	1,073,872
Increase (Decrease) in Notes Payable, Current	0	500
5.370% senior notes, Series D, quarterly interest payments, balloon due 2015
Debt Instrument [Line Items]
Current portion of senior notes			$ 25,000
5.660% senior notes, Series C, semi-annual interest payments, balloon due 2016
Debt Instrument [Line Items]
Current portion of senior notes	100,000	0
4.500% senior notes, Series E, quarterly interest payments, balloon due 2018
Debt Instrument [Line Items]
Total notes	0	100,000
4.200% senior notes, semi-annual interest payments, balloon due 2024
Debt Instrument [Line Items]
Total notes	498,943	498,785
5-year term loan facility, periodic interest and principal payments, LIBOR plus up to 1.750%, expires June 28, 2022
Debt Instrument [Line Items]
Current portion of loan facility	20,000	55,000
Long-term credit agreements	365,000	426,250
5-year revolving loan facility, periodic interest payments, currently LIBOR plus up to 1.500%, plus commitment fees up to 0.250%, expires June 28, 2022
Debt Instrument [Line Items]
Long-term credit agreements	$ 0	$ 0

Long-Term Debt - Long-Term De67

Long-Term Debt - Long-Term Debt Instrument (Additional Information) (Detail)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage		0.81%
5.660% senior notes, Series C, semi-annual interest payments, balloon due 2016
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	4.50%	4.50%
4.500% senior notes, Series E, quarterly interest payments, balloon due 2018
Debt Instrument [Line Items]
Debt instrument maturity year	2,018	2,018
4.200% senior notes, semi-annual interest payments, balloon due 2024
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	4.20%	4.20%
Debt instrument maturity year	2,024	2,024
5-year term loan facility, periodic interest and principal payments, LIBOR plus up to 1.750%, expires June 28, 2022
Debt Instrument [Line Items]
Line of credit facility, expiration period	5 years	5 years
Line of credit facility, expiration date	Jun. 28, 2022	May 20, 2019
5-year term loan facility, periodic interest and principal payments, LIBOR plus up to 1.750%, expires June 28, 2022 | LIBOR
Debt Instrument [Line Items]
Debt instrument, variable interest rate	1.75%	1.75%
5-year revolving loan facility, periodic interest payments, currently LIBOR plus up to 1.500%, plus commitment fees up to 0.250%, expires June 28, 2022
Debt Instrument [Line Items]
Line of credit facility, expiration period	5 years	5 years
Line of credit facility, commitment fee percentage	0.25%	0.25%
Line of credit facility, expiration date	Jun. 28, 2022	May 20, 2019
5-year revolving loan facility, periodic interest payments, currently LIBOR plus up to 1.500%, plus commitment fees up to 0.250%, expires June 28, 2022 | LIBOR
Debt Instrument [Line Items]
Debt instrument, variable interest rate	1.50%	1.50%

Long-Term Debt - Narrative (Det

Long-Term Debt - Narrative (Detail)

May 20, 2014USD ($)extension

Sep. 30, 2017USD ($)

Dec. 31, 2017USD ($)

Dec. 31, 2016USD ($)

Mar. 31, 2018USD ($)

Jun. 28, 2017USD ($)

Dec. 22, 2016USD ($)

Jan. 15, 2015USD ($)

Sep. 18, 2014USD ($)

Apr. 17, 2014USD ($)

Sep. 15, 2011USD ($)

Feb. 01, 2008USD ($)

Dec. 22, 2006USD ($)

Debt Instrument [Line Items]

Proceeds from Issuance of Debt

$ 2,800,000

Write off of Deferred Debt Issuance Cost

200,000

Debt Issuance Costs, Noncurrent, Net

$ 1,600,000

Debt instrument interest rate stated percentage

0.81%

Credit facility, outstanding amount

$ 365,000,000

$ 426,250,000

Revolving and term loan

385,000,000

Potential increased in line of credit facility

$ 500,000,000

Unsecured revolving credit facility

$ 400,000,000

800,000,000

Debt Instrument, Periodic Payment, Principal

5,000,000

Unsecured term loans

385,000,000

550,000,000

Outstanding debt balance

976,141,000

1,073,872,000

Notes Payable, Current

500,000

Senior Notes Due Two Thousand Sixteen [Member]

Debt Instrument [Line Items]

Current portion of senior notes

$ 25,000,000

5.370% senior notes, Series D, quarterly interest payments, balloon due 2015

Debt Instrument [Line Items]

Current portion of senior notes

$ 25,000,000

Credit Agreement

Debt Instrument [Line Items]

Credit facility, outstanding amount

481,300,000

529,400,000

Number of extension periods | extension

2

Extension period

1 year

Unsecured revolving credit facility

$ 1,350,000,000

Unsecured Senior Notes

Debt Instrument [Line Items]

Debt instrument interest rate stated percentage

4.20%

Debt instrument, face amount

$ 500,000,000

Outstanding debt balance

500,000,000

Term Loan

Debt Instrument [Line Items]

Credit facility, outstanding amount

$ 550,000,000

Debt Instrument, Periodic Payment, Principal

$ 67,500,000

Revolving Credit Facility

Debt Instrument [Line Items]

Credit facility, outstanding amount

$ 375,000,000

$ 475,000,000

Proceeds from lines of credit

0

Uncommitted Facility | New Master Agreement

Debt Instrument [Line Items]

Credit facility, outstanding amount

$ 0

Master Agreement

Debt Instrument [Line Items]

Unsecured senior notes outstanding

$ 100,000,000

Master Agreement | Series C

Debt Instrument [Line Items]

Unsecured senior notes outstanding

$ 25,000,000

$ 25,000,000

Debt instrument interest rate stated percentage

5.66%

Master Agreement | Series D

Debt Instrument [Line Items]

Debt instrument interest rate stated percentage

5.37%

Master Agreement | Series E

Debt Instrument [Line Items]

Unsecured senior notes outstanding

$ 100,000,000

Debt instrument interest rate stated percentage

4.50%

LIBOR

Debt Instrument [Line Items]

30-day Adjusted LIBOR Rate

1.625%

Minimum | Revolving Credit Facility

Debt Instrument [Line Items]

Facility fee

0.15%

Minimum | LIBOR | Term Loan

Debt Instrument [Line Items]

Debt instrument, variable interest rate

1.00%

Minimum | LIBOR | Revolving Credit Facility

Debt Instrument [Line Items]

Debt instrument, variable interest rate

0.85%

Maximum | Revolving Credit Facility

Debt Instrument [Line Items]

Facility fee

0.25%

Maximum | LIBOR | Term Loan

Debt Instrument [Line Items]

Debt instrument, variable interest rate

1.75%

Maximum | LIBOR | Revolving Credit Facility

Debt Instrument [Line Items]

Debt instrument, variable interest rate

1.50%

Scenario, Forecast [Member]

Debt Instrument [Line Items]

Unsecured senior notes outstanding

$ 5,000,000

Long-Term Debt Details (Details

Long-Term Debt Details (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Debt Disclosure [Abstract]
Interest	$ 36,172	$ 37,652	$ 37,542
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months	120,000
Long-term Debt, Maturities, Repayments of Principal in Year Two	30,000
Long-term Debt, Maturities, Repayments of Principal in Year Three	40,000
Long-term Debt, Maturities, Repayments of Principal in Year Four	40,000
Long-term Debt, Maturities, Repayments of Principal in Year Five	255,000
Long-term Debt, Maturities, Repayments of Principal after Year Five	$ 500,000

Income Taxes (Details)

Income Taxes (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2013
Income Tax Contingency [Line Items]
Operating Loss Carryforwards State	$ 52,200,000
Operating Loss Carryforwards	100,000
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities	(126,000)	$ (205,000)	$ (302,000)
Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions	0	(41,000)	0
Deferred Tax Assets, Valuation Allowance	(893,000)	(700,000)
Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions	1,070,000	412,000	773,000
Deferred income taxes, net	256,185,000	357,686,000
Deferred Tax Assets, Operating Loss Carryforwards	2,434,000	2,394,000
Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Employee Compensation	36,701,000	44,912,000
Liability for Uncertain Tax Positions, Current	228,608	86,191	102,171
Income Taxes Paid	$ 152,024,000	143,111,000	132,874,000
Document Period End Date	Dec. 31, 2017
Unrecognized Tax Benefits	$ 1,694,000	750,258	$ 583,977	$ 113,000
Deferred Tax Liabilities, Property, Plant and Equipment	2,723,000	6,425,000
deferred profit sharing contingent commissions	$ 7,107,000	$ 10,567,000
Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount	35.00%	35.00%	35.00%
Current Federal Tax Expense (Benefit)	$ 129,954,000	$ 126,145,000	$ 118,490,000
Current State and Local Tax Expense (Benefit)	21,392,000	21,110,000	17,625,000
Current Foreign Tax Expense (Benefit)	929,000	590,000	430,000
Deferred Federal Income Tax Expense (Benefit)	18,999,000	15,551,000	18,416,000
Current Income Tax Expense (Benefit)	152,275,000	147,845,000	136,545,000
Deferred State and Local Income Tax Expense (Benefit)	2,984,000	2,612,000	4,280,000
Deferred Foreign Income Tax Expense (Benefit)	$ 0	0	0
Deferred Foreign Income Tax Expense (Benefit)	As of December 31, 2017, the Company has estimated $20.9 million of cash and cash equivalent balances related to accumulated earnings associated with our international operations.
Summary of Income Tax Contingencies [Table Text Block]	$ (102,183,000)	18,163,000	22,696,000
Income Tax Expense (Benefit)	$ (50,092,000)	$ (166,008,000)	$ (159,241,000)
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent	3.80%	3.90%	3.90%
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Share-based Compensation Cost, Percent	0.30%	0.30%	0.30%
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Meals and Entertainment, Percent	0.30%	0.30%	0.30%
Tax Reform Act Deferred Tax Revaluation and Transition Tax Impact	(26.90%)
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Other, Percent	(1.40%)	(0.30%)	0.10%
Effective Income Tax Rate Reconciliation, Percent	11.10%	39.20%	39.60%
Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals	$ 7,534,000	$ 14,032,000
Net Unrealized Holding Gain on Available for Sale Securities	(6,000)	(12,000)
Deferred Tax Liabilities, Goodwill and Intangible Assets	306,351,000	422,478,000
Non Current Deferred Tax Liability	309,068,000	428,891,000
Deferred Tax Assets, Net, Noncurrent	$ 52,883,000	$ 71,205,000

Income Taxes Effective Income T

Income Taxes Effective Income Tax Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Contingency [Line Items]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	35.00%	35.00%	35.00%
Income Tax Expense (Benefit)	$ (50,092)	$ (166,008)	$ (159,241)
Tax Cuts and Jobs Act 2017 [Member]
Income Tax Contingency [Line Items]
Other Tax Expense (Benefit)	$ 3,200
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%
Income Tax Expense (Benefit)	$ 120,900
Taxes Payable	3,300
Deferred Tax Liabilities, Deferred Expense	$ 124,166

Employee Savings Plan (Details)

Employee Savings Plan (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Employee Savings Plan [Abstract]
Compensation and Employee Benefit Plans [Text Block]	Employee Savings Plan The Company has an Employee Savings Plan (401(k)) in which substantially all employees with more than 30 days of service are eligible to participate. Under this plan, Brown & Brown makes matching contributions of up to 4.0% of each participant’s annual compensation. Prior to 2014, the Company’s matching contribution was up to 2.5% of each participant’s annual compensation with an additional discretionary profit-sharing contribution each year, which equaled 1.5% of each eligible employee’s compensation. The Company’s contributions to the plan totaled $19.6 million in 2017, $19.3 million in 2016 and $17.8 million
Service Period Eligible to Participate for Employee Savings Plan	$ 30
Defined Contribution Plan, Employer Matching Contribution, Percent of Match	4.00%		2.50%
Discretionary Profit Sharing Contribution Percentage of Employees Salary	1.50%
Defined Benefit Plan, Contributions by Employer	$ 19,600,000	$ 19,300,000	$ 17,800,000

Stock Based Compensation (Detai

Stock Based Compensation (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	12 Months Ended
	Jul. 31, 2009	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Apr. 28, 2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price		$ 0	$ 18.48	$ 18.48	$ 18.57
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number		0	175,000	269,589	470,356
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term			1 year 2 months 12 days	2 years 2 months 12 days	3 years 1 month 6 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number		0	175,000	164,589
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period		0	0	0
Maximum​Number​OfShares​Available​ToBe​Granted​Under​Award​Stock​Plan		14,400,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross		5,156,954
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant		0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value		$ 6.3	$ 18.1	$ 6.8
Incremental​Increases​InAverage​Stock​Price​From​Initial​Grant​Price		20.00%
Share-based Compensation Arrangement by Share-based Payment Award, Award Requisite Service Period	20 years	15 years
Attainment​Age​OfStock​Plan		attainment of age 64
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Awarded​Shares​Outstanding​Number		847,238
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Distributed​Shares​Outstanding​Number		4,309,716
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Lower Range Limit		$ 15.58
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Upper Range Limit		$ 25.68
PerformanceStock​Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Vested​InPeriod​Awarded​Shares		138,801	506,422	208,889
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period		(17,236)	(92,517)	(117,528)
Share​Based​Compensation​Arrangement​BySharebased​Payment​Award​Equity​Instruments​Other​Than​Options​Awarded​InPeriod		0	4,000	0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period		0	0	0
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Grants​InPeriod​Prior​Year​Awards​Issued​Granted​InCurrent​Year		0	0	0
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Grants​Not​Yet​Awarded​InPeriod		0	0	0
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Awarded​InPeriod​Weighted​Average​Grant​Date​Fair​Value		0	0	0
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Not​Yet​Awarded​InPeriod		0	(4,000)	0
ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageGrantDateFairValue		10.32	10.23	9.03	8.71
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value		$ 9.61	$ 6.39	$ 5.55
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period		(138,801)	(506,422)	(208,889)
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Forfeited​InPeriod​Awarded​Shares		(17,236)	(88,517)	(100,110)
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Forfeited​InPeriod​Not​Yet​Awarded​Shares		0	(4,000)	(17,418)
ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodSharesNotAwarded		0	0	0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value		$ 10.47	$ 10.52	$ 9.78
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Granted​Shares​Outstanding​Number		847,238	1,003,275	1,602,214	1,928,631
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Shares​Not​Yet​Awarded​Outstanding​Number		0	0	8,000	25,418
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value		$ 0	$ 0	$ 0
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Awarded​Shares​Outstanding​Number		847,238	1,003,275	1,594,214	1,903,213
Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Vested​InPeriod​Awarded​Shares		(242,457)	166,884	0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period		(171,060)	(954,131)	(863,241)
Share​Based​Compensation​Arrangement​BySharebased​Payment​Award​Equity​Instruments​Other​Than​Options​Awarded​InPeriod		163,404	1,431,319	0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period		696,456	972,099	481,166
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Grants​InPeriod​Prior​Year​Awards​Issued​Granted​InCurrent​Year		120,667	182,653	164,646
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Grants​Not​Yet​Awarded​InPeriod				316,520
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Awarded​InPeriod​Weighted​Average​Grant​Date​Fair​Value		31.44	24.93	0
Share​Based​Compensation​Arrangement​BySharebased​Payment​Award​Equity​Instruments​GrantedShares​Awarded​InPeriod		0	0	0
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Not​Yet​Awarded​InPeriod		(163,404)	(1,431,319)	0
ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageGrantDateFairValue		31.16	29.96	28.74		28.19
Stock Issued During Period, Shares, Share-based Compensation, Gross			16,860	15,700	11,350
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant		4,197,920
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value		$ 25.22	$ 27.31	$ 0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period		(242,457)	(166,884)	0
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Forfeited​InPeriod​Awarded​Shares		(38,106)	(175,788)	(95,542)
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Forfeited​InPeriod​Not​Yet​Awarded​Shares		(132,954)	(778,343)	(767,699)
ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodSharesNotAwarded		0	0	0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value		$ 29.77	$ 25.34	$ 26.32
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Granted​Shares​Outstanding​Number		6,410,995	6,128,056	6,276,972		6,659,047
Shares​Available​For​Issuance​Under​Stock​Incentive​Plan							6,046,768
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Shares​Not​Yet​Awarded​Outstanding​Number		4,006,193	3,726,762	5,146,978		5,598,157
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value		$ 41.65	$ 35.52	$ 31.74
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Awarded​Shares​Outstanding​Number		2,404,802	2,401,294	1,129,994		1,060,890
Employee Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized		17,000,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant		4,151,251

Stock Based Compensation Summ74

Stock Based Compensation Summary of PSP Activity (Details) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2013
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Awarded​Shares​Outstanding​Number	847,238
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	0	0	0
Stock Incentive Plan [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageGrantDateFairValue	31.16	29.96	28.74	28.19
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Granted​Shares​Outstanding​Number	6,410,995	6,128,056	6,276,972	6,659,047
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Awarded​Shares​Outstanding​Number	2,404,802	2,401,294	1,129,994	1,060,890
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Shares​Not​Yet​Awarded​Outstanding​Number	4,006,193	3,726,762	5,146,978	5,598,157
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 41.65	$ 35.52	$ 31.74
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	696,456	972,099	481,166
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Grants​InPeriod​Prior​Year​Awards​Issued​Granted​InCurrent​Year	120,667	182,653	164,646
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Grants​Not​Yet​Awarded​InPeriod			316,520
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Awarded​InPeriod​Weighted​Average​Grant​Date​Fair​Value	31.44	24.93	0
Share​Based​Compensation​Arrangement​BySharebased​Payment​Award​Equity​Instruments​GrantedShares​Awarded​InPeriod	0	0	0
Share​Based​Compensation​Arrangement​BySharebased​Payment​Award​Equity​Instruments​Other​Than​Options​Awarded​InPeriod	163,404	1,431,319	0
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Not​Yet​Awarded​InPeriod	(163,404)	(1,431,319)	0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value	$ 25.22	$ 27.31	$ 0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period	242,457	166,884	0
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Vested​InPeriod​Awarded​Shares	242,457	(166,884)	0
ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodSharesNotAwarded	0	0	0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value	$ 29.77	$ 25.34	$ 26.32
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period	(171,060)	(954,131)	(863,241)
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Forfeited​InPeriod​Awarded​Shares	(38,106)	(175,788)	(95,542)
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Forfeited​InPeriod​Not​Yet​Awarded​Shares	(132,954)	(778,343)	(767,699)
Time-Based [Member] | Stock Incentive Plan [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested, Number of Shares	120,667	182,653	164,646
Perfomance Based [Member] | Stock Incentive Plan [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Grants​Not​Yet​Awarded​InPeriod	575,789	789,446	316,520
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Not​Yet​Awarded​InPeriod	163,404	1,435,319	0

Stock Based Compensation Stoc75

Stock Based Compensation Stock Incentive Plan (Details) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Apr. 21, 2000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price	$ 0	$ 18.48	$ 18.48
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross	5,156,954
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	0	0	0
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Awarded​Shares​Outstanding​Number	847,238
PerformanceStock​Plan [Member]
ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageGrantDateFairValue	10.32	10.23	9.03	8.71
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 0	$ 0	$ 0
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Awarded​InPeriod​Weighted​Average​Grant​Date​Fair​Value	0	0	0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value	$ 9.61	$ 6.39	$ 5.55
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value	$ 10.47	$ 10.52	$ 9.78
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Granted​Shares​Outstanding​Number	847,238	1,003,275	1,602,214	1,928,631
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	0	0	0
Share​Based​Compensation​Arrangement​BySharebased​Payment​Award​Equity​Instruments​Other​Than​Options​Awarded​InPeriod	0	4,000	0
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Not​Yet​Awarded​InPeriod	0	(4,000)	0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period	138,801	506,422	208,889
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period	(17,236)	(92,517)	(117,528)
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Awarded​Shares​Outstanding​Number	847,238	1,003,275	1,594,214	1,903,213
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Grants​InPeriod​Prior​Year​Awards​Issued​Granted​InCurrent​Year	0	0	0
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Vested​InPeriod​Awarded​Shares	(138,801)	(506,422)	(208,889)
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Forfeited​InPeriod​Awarded​Shares	(17,236)	(88,517)	(100,110)
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Shares​Not​Yet​Awarded​Outstanding​Number	0	0	8,000	25,418
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Grants​Not​Yet​Awarded​InPeriod	0	0	0
ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodSharesNotAwarded	0	0	0
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Forfeited​InPeriod​Not​Yet​Awarded​Shares	0	(4,000)	(17,418)
Stock Incentive Plan [Member]
Stock Issued During Period, Shares, Share-based Compensation, Gross		16,860	15,700	11,350
ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageGrantDateFairValue	31.16	29.96	28.74		28.19
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 41.65	$ 35.52	$ 31.74
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Awarded​InPeriod​Weighted​Average​Grant​Date​Fair​Value	31.44	24.93	0
Share​Based​Compensation​Arrangement​BySharebased​Payment​Award​Equity​Instruments​GrantedShares​Awarded​InPeriod	0	0	0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value	$ 25.22	$ 27.31	$ 0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value	$ 29.77	$ 25.34	$ 26.32
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Granted​Shares​Outstanding​Number	6,410,995	6,128,056	6,276,972		6,659,047
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	696,456	972,099	481,166
Share​Based​Compensation​Arrangement​BySharebased​Payment​Award​Equity​Instruments​Other​Than​Options​Awarded​InPeriod	163,404	1,431,319	0
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Not​Yet​Awarded​InPeriod	(163,404)	(1,431,319)	0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period	242,457	166,884	0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period	(171,060)	(954,131)	(863,241)
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Awarded​Shares​Outstanding​Number	2,404,802	2,401,294	1,129,994		1,060,890
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Grants​InPeriod​Prior​Year​Awards​Issued​Granted​InCurrent​Year	120,667	182,653	164,646
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Vested​InPeriod​Awarded​Shares	242,457	(166,884)	0
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Forfeited​InPeriod​Awarded​Shares	(38,106)	(175,788)	(95,542)
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Shares​Not​Yet​Awarded​Outstanding​Number	4,006,193	3,726,762	5,146,978		5,598,157
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Grants​Not​Yet​Awarded​InPeriod			316,520
ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodSharesNotAwarded	0	0	0
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Forfeited​InPeriod​Not​Yet​Awarded​Shares	(132,954)	(778,343)	(767,699)
Incentive Stock Option Plan [Member] | Maximum [Member]
Shares held in Employee Stock Option Plan, Suspense Shares						4,800,000
Perfomance Based [Member] | Stock Incentive Plan [Member]
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Not​Yet​Awarded​InPeriod	163,404	1,435,319	0
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Grants​Not​Yet​Awarded​InPeriod	575,789	789,446	316,520

Stock Based Compensation Non Ca

Stock Based Compensation Non Cash Stock Based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Compensation Cost for Share-based Payment Arrangements, Allocation of Share-based Compensation Costs by Plan [Table Text Block]	The non-cash stock-based compensation expense for the years ended December 31 is as follows: (in thousands) 2017 2016 2015 Stock Incentive Plan $ 24,899 $ 11,049 $ 11,111 Employee Stock Purchase Plan 4,025 3,698 3,430 Performance Stock Plan 1,707 1,305 972 Incentive Stock Option Plan — — — Total $ 30,631 $ 16,052 $ 15,513
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation	$ 30,631	$ 16,052	$ 15,513
Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation	24,899	11,049	11,111
PerformanceStock​Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation	1,707	1,305	972
Incentive Stock Option Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation	0	0	0
Employee Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation	$ 4,025	$ 3,698	$ 3,430

Stock Based Compensation Share

Stock Based Compensation Share Based Compensation Shares Authorized under Stock Option Plans, Exercise Price Range (Details) - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2017
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number	175,000	269,589	470,356	0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term	1 year 2 months 12 days	2 years 2 months 12 days	3 years 1 month 6 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price	$ 18.48	$ 18.48	$ 18.57	$ 0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number	175,000	164,589		0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price	$ 18.48	$ 18.48		$ 0
PerformanceStock​Plan [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageGrantDateFairValue	10.23	9.03	8.71	10.32

Stock Based Compensation Summ78

Stock Based Compensation Summary of Stock Options (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number	0	175,000	269,589	470,356
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price	$ 0	$ 18.48	$ 18.48	$ 18.57
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term		1 year 2 months 12 days	2 years 2 months 12 days	3 years 1 month 6 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value	$ 0	$ 4,616	$ 2,395	$ 5,087
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	0	0	0
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price	$ 0	$ 0	$ 0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period	175,000	64,589	151,767
Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price	$ 18.48	$ 18.48	$ 18.48
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period	0	30,000	49,000
Share-based Compensation Arrangements by Share-based Payment Award, Options, Forfeitures in Period, Weighted Average Exercise Price	$ 0	$ 18.48	$ 19.36
Share-based Compensation Arrangement by Share-based Payment Award, Options, Expirations in Period	0	0	0
Share-based Compensation Arrangements by Share-based Payment Award, Options, Expirations in Period, Weighted Average Exercise Price	$ 0	$ 0	$ 0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Number	0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Exercise Price	$ 0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Aggregate Intrinsic Value	$ 0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number	0	175,000	164,589
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price	$ 0	$ 18.48	$ 18.48
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term		1 year 2 months 12 days	2 years 2 months 12 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value	$ 0	$ 4,616	$ 2,241
Stock Incentive Plan [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Not​Yet​Awarded​InPeriod	(163,404)	(1,431,319)	0
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Grants​InPeriod​Prior​Year​Awards​Issued​Granted​InCurrent​Year	120,667	182,653	164,646
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	696,456	972,099	481,166

Stock Based Compensation Employ

Stock Based Compensation Employee Stock Purchase Plan Details (Details)	12 Months Ended
	Dec. 31, 2017USD ($)shares	Aug. 31, 2017$ / shares	Jul. 31, 2017USD ($)$ / sharesshares	Dec. 31, 2016USD ($)shares	Aug. 31, 2016$ / shares	Jul. 31, 2016USD ($)$ / sharesshares	Dec. 31, 2015USD ($)shares	Aug. 31, 2015$ / shares	Jul. 31, 2015USD ($)$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	0
Share-based Compensation Arrangement by Share-based Payment Award, Maximum Employee Subscription Rate	10.00%
Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	4,197,920
Employee Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	4,151,251
Threshold​Period​Worked​Per​Week​ByEmployees	20
Allotted​Value​Maximum | $	$ 25,000
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Subscription​Period​Beginning	--08-01
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Subscription​Period​Ending	--07-31
Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent	85.00%
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Percent​OfMarket​Price	15.00%
Value​OfOne​Year​Stock​Option​Percentage	85.00%
Estimated​Fair​Value​Per​Share​Option | $ / shares		$ 8.64			$ 7.61			$ 6.43
Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period			529,012			514,665			539,389
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Shares​Issued​Aggregate​Purchase​Value | $			$ 16,400,000			$ 15,000,000			$ 14,400,000
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Shares​Issued​Aggregate​Purchase​Price​Per​Share | $ / shares			$ 31.03			$ 29.23			$ 26.62
Shares held in Employee Stock Option Plan, Suspense Shares	217,514			247,023			231,803
Cash​Received​From​Proceeds​ByParticipants | $	$ 8,200,000			$ 7,700,000			$ 6,800,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	17,000,000

Stock Based Compensation Incent

Stock Based Compensation Incentive Stock Option Plan (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Apr. 21, 2000
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value	$ 4.7	$ 1	$ 2.2
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	0
PerformanceStock​Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Not​Yet​Awarded​InPeriod	0	(4,000)	0
Incentive Stock Option Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage​OfPre​Tax​Income	15.00%
Incentive Stock Option Plan [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Options​Vesting​Period	10 years
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	6 years
Shares held in Employee Stock Option Plan, Suspense Shares				4,800,000
Incentive Stock Option Plan [Member] | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Options​Vesting​Period	1 year
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	3 years

Stock Based Compensation Unreco

Stock Based Compensation Unrecognized Compensation Costs (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized	$ 87.9
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	3 years 7 months 13 days

Stock Based Compensation Detail

Stock Based Compensation Details (Details)	Dec. 31, 2017shares
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Maximum​Number​OfShares​Available​ToBe​Granted​Under​Award​Stock​Plan	14,400,000

Stock Based Compensation Schedu

Stock Based Compensation Schedule of compensation cost for share-based payment arrangements, allocation of share-based compensation costs by plan (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation	$ 30,631	$ 16,052	$ 15,513
Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation	24,899	11,049	11,111
PerformanceStock​Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation	1,707	1,305	972
Incentive Stock Option Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation	$ 0	$ 0	$ 0

Stock Based Compensation Sche84

Stock Based Compensation Schedule of Share Based Compensation, Stock Options Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Apr. 28, 2010
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross	5,156,954
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Awarded​Shares​Outstanding​Number	847,238
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number	0	175,000	269,589	470,356
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price	$ 0	$ 18.48	$ 18.48	$ 18.57
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term		1 year 2 months 12 days	2 years 2 months 12 days	3 years 1 month 6 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value	$ 0	$ 4,616	$ 2,395	$ 5,087
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	0	0	0
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price	$ 0	$ 0	$ 0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period	(175,000)	(64,589)	(151,767)
Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price	$ 18.48	$ 18.48	$ 18.48
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period	0	(30,000)	(49,000)
Share-based Compensation Arrangements by Share-based Payment Award, Options, Forfeitures in Period, Weighted Average Exercise Price	$ 0	$ 18.48	$ 19.36
Share-based Compensation Arrangement by Share-based Payment Award, Options, Expirations in Period	0	0	0
Share-based Compensation Arrangements by Share-based Payment Award, Options, Expirations in Period, Weighted Average Exercise Price	$ 0	$ 0	$ 0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Number	0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Exercise Price	$ 0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Aggregate Intrinsic Value	$ 0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number	0	175,000	164,589
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price	$ 0	$ 18.48	$ 18.48
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term		1 year 2 months 12 days	2 years 2 months 12 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value	$ 0	$ 4,616	$ 2,241
Stock Incentive Plan [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Not​Yet​Awarded​InPeriod	(163,404)	(1,431,319)	0
Shares​Available​For​Issuance​Under​Stock​Incentive​Plan						6,046,768
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Granted​Shares​Outstanding​Number	6,410,995	6,128,056	6,276,972		6,659,047
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 41.65	$ 35.52	$ 31.74
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Awarded​Shares​Outstanding​Number	2,404,802	2,401,294	1,129,994		1,060,890
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Shares​Not​Yet​Awarded​Outstanding​Number	4,006,193	3,726,762	5,146,978		5,598,157
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	696,456	972,099	481,166
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Grants​Not​Yet​Awarded​InPeriod			316,520
Stock Issued During Period, Shares, Share-based Compensation, Gross		16,860	15,700	11,350
PerformanceStock​Plan [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Not​Yet​Awarded​InPeriod	0	(4,000)	0
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Granted​Shares​Outstanding​Number	847,238	1,003,275	1,602,214	1,928,631
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 0	$ 0	$ 0
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Awarded​Shares​Outstanding​Number	847,238	1,003,275	1,594,214	1,903,213
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Shares​Not​Yet​Awarded​Outstanding​Number	0	0	8,000	25,418
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	0	0	0
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Grants​Not​Yet​Awarded​InPeriod	0	0	0
Perfomance Based [Member] | Stock Incentive Plan [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Not​Yet​Awarded​InPeriod	163,404	1,435,319	0
Share​Based​Compensation​Arrangement​ByShare​Based​Payment​Award​Equity​Instruments​Other​Than​Options​Grants​Not​Yet​Awarded​InPeriod	575,789	789,446	316,520

Supplemental Disclosures of C85

Supplemental Disclosures of Cash Flow Information and Non-Cash Financing and Investing Activities - Significant Non-Cash Investing and Financing Activities (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted Cash and Cash Equivalents	$ 250,705,000	$ 265,637,000	$ 229,753,000
Cash and Cash Equivalents, at Carrying Value	573,383,000	515,646,000	443,420,000
Cash paid during the period for:
Interest	36,172,000	37,652,000	37,542,000
Income taxes	152,024,000	143,111,000	132,874,000
Significant non-cash investing and financing activities
Other payables issued for purchased customer accounts	11,708,000	10,664,000	10,029,000
Estimated acquisition earn-out payables and related charges	6,921,000	4,463,000	36,899,000
Notes Assumed	0	492,000	0
Notes received on the sale of fixed assets and customer accounts	0	22,000	7,755,000
Cash and Cash Equivalents inclusive of Restricted Cash [Member]
Restricted Cash and Cash Equivalents Items [Line Items]
Cash and Cash Equivalents, at Carrying Value	$ 824,088,000	$ 781,283,000	$ 673,173,000

Supplemental Disclosures of C86

Supplemental Disclosures of Cash Flow Information and Non-Cash Financing and Investing Activities Restricted Cash (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash and Cash Equivalents, at Carrying Value	$ 573,383,000	$ 515,646,000	$ 443,420,000
Restricted Cash and Cash Equivalents	250,705,000	265,637,000	229,753,000
Cash and Cash Equivalents inclusive of Restricted Cash [Member]
Cash and Cash Equivalents, at Carrying Value	$ 824,088,000	$ 781,283,000	$ 673,173,000

Commitments and Contingencies87

Commitments and Contingencies (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Operating Leases, Rent Expense	$ 51,000	$ 49,300	$ 46,000
Operating Leases, Future Minimum Payments Due, Next Twelve Months	42,970
Operating Leases, Future Minimum Payments, Due in Two Years	39,005
Operating Leases, Future Minimum Payments, Due in Three Years	34,236
Operating Leases, Future Minimum Payments, Due in Four Years	27,715
Operating Leases, Future Minimum Payments, Due in Five Years	21,996
Operating Leases, Future Minimum Payments, Due Thereafter	44,496
Operating Leases, Future Minimum Payments Due	$ 210,418	$ 213,200

Quarterly Operating Results (De

Quarterly Operating Results (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Total revenues	$ 474,316	$ 475,646	$ 466,305	$ 465,080	$ 433,664	$ 462,274	$ 446,518	$ 424,173	$ 1,881,347	$ 1,766,629	$ 1,660,509
Operating Expenses	367,982	351,227	358,303	354,113	338,763	345,302	337,441	321,624	1,431,625	1,343,130	1,257,950
Income before income taxes	106,334	124,419	108,002	110,967	94,901	116,972	109,077	102,549	449,722	423,499	402,559
Net Income (Loss) Attributable to Parent	$ 187,505	$ 75,913	$ 66,102	$ 70,110	$ 57,626	$ 71,545	$ 66,250	$ 62,070	$ 399,630	$ 257,491	$ 243,318
Earnings Per Share, Basic	$ 0.0135	$ 0.0054	$ 0.0047	$ 0.0050	$ 0.0041	$ 0.0051	$ 0.0047	$ 0.0045	$ 2.86	$ 1.84	$ 1.72
Diluted (in dollars per share)	$ 0.0132	$ 0.0053	$ 0.0046	$ 0.0049	$ 0.0041	$ 0.0050	$ 0.0047	$ 0.0044	$ 2.81	$ 1.82	$ 1.70

Segment Information - Additiona

Segment Information - Additional Information (Detail) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017USD ($)	Sep. 30, 2017USD ($)	Jun. 30, 2017USD ($)	Mar. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Sep. 30, 2016USD ($)	Jun. 30, 2016USD ($)	Mar. 31, 2016USD ($)	Dec. 31, 2017USD ($)Segment	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | Segment									4
Total revenues	$ 474,316	$ 475,646	$ 466,305	$ 465,080	$ 433,664	$ 462,274	$ 446,518	$ 424,173	$ 1,881,347	$ 1,766,629	$ 1,660,509
London, Bermuda and Cayman Islands
Segment Reporting Information [Line Items]
Total revenues									$ 15,900	$ 14,500	$ 13,400

Segment Information - Summarize

Segment Information - Summarized Financial Information Reportable Segments (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Total revenues	$ 474,316	$ 475,646	$ 466,305	$ 465,080	$ 433,664	$ 462,274	$ 446,518	$ 424,173	$ 1,881,347	$ 1,766,629	$ 1,660,509
Investment income									1,626	1,456	1,004
Amortization									85,446	86,663	87,421
Depreciation									22,698	21,003	20,890
Interest expense									38,316	39,481	39,248
Income before income taxes	106,334	$ 124,419	$ 108,002	$ 110,967	94,901	$ 116,972	$ 109,077	$ 102,549	449,722	423,499	402,559
Total assets	5,747,550				5,262,734				5,747,550	5,262,734	4,979,844
Capital expenditures									24,192	17,765	18,375
Operating Segments | Retail
Segment Reporting Information [Line Items]
Total revenues									943,460	917,406	870,346
Investment income									8	37	87
Amortization									42,164	43,447	45,145
Depreciation									5,210	6,191	6,558
Interest expense									31,133	38,216	41,036
Income before income taxes									196,616	188,001	181,938
Total assets	4,255,515				3,854,393				4,255,515	3,854,393	3,507,476
Capital expenditures									4,494	5,951	6,797
Operating Segments | National Programs
Segment Reporting Information [Line Items]
Total revenues									479,813	448,516	428,734
Investment income									384	628	210
Amortization									27,277	27,920	28,479
Depreciation									6,325	7,868	7,250
Interest expense									35,561	45,738	55,705
Income before income taxes									109,961	91,762	67,673
Total assets	3,267,486				2,711,378				3,267,486	2,711,378	2,503,537
Capital expenditures									5,936	6,977	6,001
Operating Segments | Wholesale Brokerage
Segment Reporting Information [Line Items]
Total revenues									271,737	243,103	216,996
Investment income									0	4	150
Amortization									11,456	10,801	9,739
Depreciation									1,885	1,975	2,142
Interest expense									6,263	3,976	891
Income before income taxes									68,844	62,623	64,708
Total assets	1,260,239				1,108,829				1,260,239	1,108,829	895,782
Capital expenditures									1,836	1,301	3,084
Operating Segments | Services
Segment Reporting Information [Line Items]
Total revenues									165,372	156,365	145,365
Investment income									299	283	42
Amortization									4,548	4,485	4,019
Depreciation									1,600	1,881	1,988
Interest expense									3,522	4,950	5,970
Income before income taxes									30,498	24,338	19,713
Total assets	399,240				371,645				399,240	371,645	285,459
Capital expenditures									1,033	656	1,088
Other
Segment Reporting Information [Line Items]
Total revenues									20,965	1,239	(932)
Investment income									935	504	515
Amortization									1	10	39
Depreciation									7,678	3,088	2,952
Interest expense									(38,163)	(53,399)	(64,354)
Income before income taxes									43,803	56,775	68,527
Total assets	$ (3,434,930)				$ (2,783,511)				(3,434,930)	(2,783,511)	(2,212,410)
Capital expenditures									$ 10,893	$ 2,880	$ 1,405

Losses and Loss Adjustment Re91

Losses and Loss Adjustment Reserve - Effects of Reinsurance on Premiums Written and Earned (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Written
Direct premiums	$ 604,623	$ 591,142
Assumed premiums	0	0
Ceded premiums	604,610	591,124
Net premiums	13	18
Earned
Direct premiums	592,267	592,123
Assumed premiums	0	0
Ceded premiums	592,254	592,105
Net premiums	$ 13	$ 18

Losses and Loss Adjustment Re92

Losses and Loss Adjustment Reserve - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2017USD ($)Reinsurer	Dec. 31, 2016USD ($)
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Ceded rate of premiums under insurance program	100.00%
Document Period End Date	Dec. 31, 2017
Premiums written net	$ 604,610,000	$ 591,124,000
Reinsurance Recoverables on Unpaid Losses, Gross	477,800,000	78,100,000
Prepaid reinsurance premiums	321,017,000	308,661,000
Increase (Decrease) in Loss and Loss Adjustment Expense Reserve	1,100,000
Reserve For Losses And Loss Adjustment Expenses For Reinsurance Liability	$ 477,800,000	78,100,000
Number of reinsurers | Reinsurer	2
Wright National Flood Insurance Company [Member]
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Ceded rate of premiums under insurance program	100.00%
Percentage of reinsurance recoverables allowance	30.90%
Premiums written net	$ 602,900,000	589,500,000
Wright National Flood Insurance Company [Member] | Quota Share Agreement
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Effective cedes rate under quota share agreement	100.00%
Commission rate, percent of ceded written premiums	30.50%
Wright National Flood Insurance Company [Member] | Quota Share Agreement | Reinsurer Concentration Risk [Member]
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Ceded amount	$ 1,700,000	$ 1,600,000
Wright National Flood Insurance Company [Member]
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Loss Adjustment Expense	16,606
Case Reserves	838,307
Liability for Unpaid Claims and Claims Adjustment Expense, Incurred but Not Reported (IBNR) Claims, Amount	$ 1,500,000

Statutory Financial Informati93

Statutory Financial Information - Additional Information (Detail) - Wright Flood - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Statutory Accounting Practices [Line Items]
Statutory capital and surplus required	$ 7,500,000
Statutory capital and surplus	28,700,000	$ 23,500,000
Statutory net Income	$ 4,800,000	$ 8,200,000

Subsidiary Dividend Restricti94

Subsidiary Dividend Restrictions - Additional Information (Detail) - Wright Flood - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2018
Dividend Restrictions [Line Items]
Dividend rate as a percentage of net income	100.00%
Statutory Dividend Payment Restrictions Disclosure	Under the insurance regulations of Texas, where WNFIC in incorporated, the maximum amount of ordinary dividends that WNFIC can pay to shareholders in a rolling twelve month period is limited to the greater of 10% of statutory adjusted capital and surplus as shown on WNFIC’s last annual statement on file with the superintendent of the Texas Department of Insurance or 100% of adjusted net income
Scenario, Forecast
Dividend Restrictions [Line Items]
Maximum dividend payout that may be made without prior approval		$ 4.8
Maximum
Dividend Restrictions [Line Items]
Dividend rate as a percentage of net income	10.00%

Shareholders' Equity - Addition

Shareholders' Equity - Additional Information (Detail) - USD ($)	12 Months Ended			48 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2017	Feb. 09, 2018	Jul. 20, 2015	Jul. 21, 2014
Accelerated Share Repurchases [Line Items]
Treasury stock shares (in shares)	8,003,197			10,718,319
Fair value of common stock repurchased	$ 257,683,000			$ 386,322,000
Stock Repurchase Program, Remaining Authorized Repurchase Amount				$ 238,700,000
Treasury Stock, Shares, Acquired				10,700,000
Accelerated Share Repurchase Agreement [Member]
Accelerated Share Repurchases [Line Items]
Treasury stock shares (in shares)	209,618	5,408,819	2,384,760	348,460
Treasury Stock Acquired, Average Cost Per Share	$ 36.53	$ 32.35	$ 31.46
Fair value of common stock repurchased	$ 7,700,000	$ 175,000,000	$ 75,000,000	$ 14,900,000
Second Accelerated Share Repurchase Agreement [Member]
Accelerated Share Repurchases [Line Items]
Treasury stock shares (in shares)				1,076,176
Fair value of common stock repurchased				$ 50,000,000
Third Accelerated Share Repurchase Agreement [Member]
Accelerated Share Repurchases [Line Items]
Stock Repurchase Program, Authorized Amount				75,000,000
Fair value of common stock repurchased				63,800,000
Maximum [Member]
Accelerated Share Repurchases [Line Items]
Stock Repurchase Program, Authorized Amount				$ 100,000,000		$ 400,000,000	$ 200,000,000
Subsequent Event [Member] | Third Accelerated Share Repurchase Program [Member]
Accelerated Share Repurchases [Line Items]
Treasury stock shares (in shares)					1,458,713
Fair value of common stock repurchased					$ 11,200,000
Share Repurchase Executed Part 2 [Member] | Second Accelerated Share Repurchase Agreement [Member]
Accelerated Share Repurchases [Line Items]
Treasury stock shares (in shares)				108,288
Fair value of common stock repurchased				$ 7,500,000
Share Repurchase Executed Part 2 [Member] | Subsequent Event [Member] | Third Accelerated Share Repurchase Program [Member]
Accelerated Share Repurchases [Line Items]
Treasury stock shares (in shares)					168,227
Share Repurchase Executed Part 1 [Member] | Second Accelerated Share Repurchase Agreement [Member]
Accelerated Share Repurchases [Line Items]
Treasury stock shares (in shares)				967,888
Fair value of common stock repurchased				$ 42,500,000
Share Repurchase Executed Part 1 [Member] | Third Accelerated Share Repurchase Agreement [Member]
Accelerated Share Repurchases [Line Items]
Treasury stock shares (in shares)				1,290,486

Fixed Income Securities (Detail

Fixed Income Securities (Details) $ in Millions	12 Months Ended
	Dec. 31, 2016USD ($)
Schedule of Available-for-sale Securities [Line Items]
Proceeds from Sale of Short-term Investments	$ 1.7

Uncategorized Items - bro-20171

Label	Element	Value
Treasury Stock, Value, Acquired, Cost Method	us-gaap_TreasuryStockValueAcquiredCostMethod	$ 386,300,000