Borrowings (Tables)

12 Months Ended

Dec. 31, 2017

Debt Disclosure [Abstract]

Amounts and Interest Rates of Short-term Borrowings

The amounts and interest rates of short-term borrowings were as follows:

	Federal Funds Purchased and Repurchase Agreements			Other Short-term Borrowings			Total
	(Dollars in thousands)
At December 31, 2017
Amount outstanding	$	175,099		$	—		$	175,099
Weighted-average interest rate		0.92	%		—			0.92	%
For the year ended December 31, 2017
Highest amount at a month-end	$	204,977		$	1,500,000
Daily-average amount outstanding		188,459			16,164		$	204,623
Weighted-average interest rate		0.69	%		1.27	%		0.74	%
At December 31, 2016
Amount outstanding	$	163,442		$	—		$	163,442
Weighted-average interest rate		0.32	%		—			0.32	%
For the year ended December 31, 2016
Highest amount at a month-end	$	225,940		$	1,974,013
Daily-average amount outstanding		203,853			689,969		$	893,822
Weighted-average interest rate		0.28	%		0.44	%		0.41	%
At December 31, 2015
Amount outstanding	$	150,546		$	1,981,636		$	2,132,182
Weighted-average interest rate		0.06	%		0.43	%		0.40	%
For the year ended December 31, 2015
Highest amount at a month-end	$	202,951		$	1,989,257
Daily-average amount outstanding		187,167			360,838		$	548,005
Weighted-average interest rate		0.08	%		0.43	%		0.31	%

Lines of Credit Under Formal Agreements

At December 31, 2017, M&T Bank had lines of credit under formal agreements as follows:

	(In thousands)
Outstanding borrowings	$	576,954
Unused		31,624,206

Long-term Borrowings

Long-term borrowings were as follows:

	December 31,
	2017		2016
	(In thousands)
Senior notes of M&T Bank:
Variable rate due 2017	$	—	$	550,000
Variable rate due 2022		249,558		—
1.25% due 2017		—		499,999
1.40% due 2017		—		749,946
1.45% due 2018		499,907		501,829
2.25% due 2019		644,977		649,012
2.30% due 2019		746,919		749,473
2.10% due 2020		743,788		749,735
2.05% due 2020		739,961		—
2.50% due 2022		638,872		—
2.90% due 2025		749,404		749,320
Advances from FHLB:
Fixed rates		576,876		1,154,737
Agreements to repurchase securities		421,771		1,084,694
Subordinated notes of Wilmington Trust Corporation (a wholly    owned subsidiary of M&T):
8.50% due 2018		200,000		207,651
Subordinated notes of M&T Bank:
6.625% due 2017		—		409,526
5.585% due 2020, variable rate commenced 2015		409,361		409,361
5.629% due 2021, variable rate commenced 2016		500,000		500,000
3.40% due 2027		491,176		—
Junior subordinated debentures of M&T associated with preferred    capital securities:
Fixed rates:
BSB Capital Trust I — 8.125%, due 2028		15,682		15,659
Provident Trust I — 8.29%, due 2028		26,847		26,293
Southern Financial Statutory Trust I — 10.60%, due 2030		6,664		6,620
Variable rates:
First Maryland Capital I — due 2027		146,794		146,256
First Maryland Capital II — due 2027		148,617		147,954
Allfirst Asset Trust — due 2029		96,640		96,494
BSB Capital Trust III — due 2033		15,464		15,464
Provident Statutory Trust III — due 2033		54,466		53,834
Southern Financial Capital Trust III — due 2033		8,051		7,968
Other		9,635		12,010
	$	8,141,430	$	9,493,835

Maturity of Long-term Borrowings

Long-term borrowings at December 31, 2017 mature as follows:

	(In thousands)
Year ending December 31:
2018	$	701,256
2019		2,282,016
2020		2,005,383
2021		502,487
2022		888,430
Later years		1,761,858
	$	8,141,430