Consolidated Statements of Cash Flows $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($)		Dec. 31, 2016 USD ($)		Dec. 31, 2015 USD ($)
Operating Activities
Net income	$ 275,474		$ 246,784		$ 226,082
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses	67,185		28,000		19,010
Depreciation, amortization, and accretion, net	59,121		58,228		56,741
Deferred income tax expense	231,056		128,837		121,904
Decrease (increase) in trading account assets	5,494		(2,327)		8,766
Originations of mortgage loans held for sale	(622,564)		(705,394)		(790,625)
Proceeds from sales of mortgage loans held for sale	642,193		724,712		807,906
Gain on sales of mortgage loans held for sale, net	(13,450)		(13,780)		(14,966)
(Increase) decrease in other assets	(80,544)	[1]	(21,697)	[1]	6,135	[1]
Increase (decrease) in other liabilities	28,651		(4,239)		(24,906)
Investment securities losses (gains), net	289		(6,011)		(2,769)
Losses and write-downs on other real estate, net	11,382		10,174		17,619
Loss on early extinguishment of debt, net	23,160		4,735		1,533
Share-based compensation expense	14,179		13,615		12,556
Net cash provided by operating activities	641,626		461,637		444,986
Investing Activities
Net cash received in acquisition	0		6,146		0
Net increase in interest earning deposits with banks	(7,591)		(1,335)		(5,577)
Net decrease in federal funds sold and securities purchased under resale agreements	10,214		11,759		3,291
Net decrease (increase) in interest bearing funds with Federal Reserve Bank	66,162		302,797		(108,525)
Proceeds from maturities and principal collections of investment securities available for sale	632,875		894,123		693,608
Proceeds from sales of investment securities available for sale	812,293		968,606		347,954
Purchases of investment securities available for sale	(1,729,902)		(2,051,283)		(1,634,531)
Proceeds from sales of loans	42,726		15,046		28,762
Proceeds from sale of other real estate	14,322		30,762		47,137
Net increase in loans	(1,060,582)		(1,129,422)		(1,411,050)
Purchase of Federal Reserve Bank capital stock	0		(97,293)		0
Purchases of bank-owned life insurance policies, net of settlements	(148,110)	[1]	(28,126)	[1]	(42,444)	[1]
Net increase in premises and equipment	(51,106)		(34,317)		(28,381)
Proceeds from sale of other assets held for sale	3,158		13,072		3,039
Net cash used in investing activities	(1,415,541)		(1,099,465)		(2,106,717)
Financing Activities
Net increase in demand and savings deposits	932,561		1,512,451		2,274,949
Net increase (decrease) in certificates of deposit	566,524		(107,893)		(565,315)
Net increase (decrease) in federal funds purchased and securities sold under repurchase agreements	1,491		(17,326)		50,109
Repayments and redemption of long-term debt	(2,250,422)		(2,263,688)		(823,899)
Proceeds from issuance of long-term debt	1,771,866		1,875,000		871,644
Dividends paid to common shareholders	(54,670)		(59,425)		(55,354)
Dividends paid to preferred shareholders	(10,238)		(10,238)		(10,238)
Stock options exercised	3,440		5,155		5,643
Earnout payment	(892)		0		0
Repurchase of common stock	(175,079)		(263,084)		(199,221)
Taxes paid related to net share settlement of equity awards	(7,993)		(5,041)		(4,984)
Net cash provided by financing activities	776,588		665,911		1,543,334
Increase (decrease) in cash and cash equivalents	2,673		28,083		(118,397)
Cash and cash equivalents at beginning of year	395,175		367,092		485,489
Cash and cash equivalents at end of year	397,848		395,175		367,092
Supplemental Cash Flow Information
Income tax payments, net	18,040		9,340		10,514
Interest paid	143,237		123,560		115,795
Non-cash Activities:
Loans foreclosed and transferred to other real estate	7,154		16,214		26,313
Premises and equipment transferred to other properties held for sale	3,283		25,231		2,340
Other assets held for sale transferred to premises and equipment	4,450		0		0
Investment securities available for sale transferred to trading account assets at fair value	0		1,890		0
Loans transferred to other loans held for sale at fair value	52,829		14,621		26,213
Dividends declared on common stock during the period but paid after period-end	17,835		0		0
Settlement of earnout payment with shares of common stock	5,460		0		0
Mortgage loans held for sale transferred to loans at fair value	0		313		659
Acquisition:
Fair value of non-cash assets acquired	0		408,054		0
Fair value of liabilities assumed	0		387,608		0
Fair value of common stock issued	$ 0		$ 26,592		$ 0

[1] Related to Synovus' early adoption of ASU 2016-15, certain prior period amounts have been reclassified between operating activities and investing activities. See "Part II - Item 8. Financial Statements and Supplementary Data - Note 1 - Summary of Significant Accounting Policies" of this Report for additional information.