SHARE CAPITAL - Dividends (Details) - CAD ($)
$ / shares in Units, $ in Millions

12 Months Ended

Mar. 15, 2019

Feb. 01, 2019

Dec. 31, 2018

Dec. 31, 2017

Common share capital

Disclosure of classes of share capital [line items]

Dividends paid

$ 1,131

$ 873

Dividends paid per share (in CAD per share)

$ 2.24

$ 2.04000

Preferred share capital

Disclosure of classes of share capital [line items]

Dividends paid

$ 122

$ 83

Series 1 preferred share

Disclosure of classes of share capital [line items]

Dividends paid

$ 11

Dividends paid per share (in CAD per share)

$ 1.062500

Series 3 preferred share

Disclosure of classes of share capital [line items]

Dividends paid

$ 7

Dividends paid per share (in CAD per share)

$ 1.175

Series 5 preferred share

Disclosure of classes of share capital [line items]

Dividends paid

$ 12

Dividends paid per share (in CAD per share)

$ 1.25

Series 7 preferred share

Disclosure of classes of share capital [line items]

Dividends paid

$ 11

Dividends paid per share (in CAD per share)

$ 1.125

Series 9 preferred share

Disclosure of classes of share capital [line items]

Dividends paid

$ 11

Dividends paid per share (in CAD per share)

$ 1.1875

Series 11 preferred share

Disclosure of classes of share capital [line items]

Dividends paid

$ 10

Dividends paid per share (in CAD per share)

$ 1.4375

Series 13 preferred share

Disclosure of classes of share capital [line items]

Dividends paid

$ 14

Dividends paid per share (in CAD per share)

$ 1.4375

Series 15 preferred share

Disclosure of classes of share capital [line items]

Dividends paid

$ 9

$ 2

Dividends paid per share (in CAD per share)

$ 1.116000

$ 0.279

Series 17 preferred share

Disclosure of classes of share capital [line items]

Dividends paid

$ 8

$ 2

Dividends paid per share (in CAD per share)

$ 1.250000

$ 0.3125

Series 19 preferred share

Disclosure of classes of share capital [line items]

Dividends paid

$ 10

$ 3

Dividends paid per share (in CAD per share)

$ 1.250000

$ 0.31250

Series 21 preferred share

Disclosure of classes of share capital [line items]

Dividends paid

$ 19

$ 0

Dividends paid per share (in CAD per share)

$ 1.200650

$ 0

Major preference share transactions | Series 1 preferred share

Disclosure of classes of share capital [line items]

Dividends proposed or declared before financial statements authorised for issue but not recognised as distribution to owners per share (in CAD per share)

$ 0.306625

Dividends proposed or declared before financial statements authorised for issue but not recognised as distribution to owners

$ 3

Major preference share transactions | Series 3 preferred share

Disclosure of classes of share capital [line items]

Dividends proposed or declared before financial statements authorised for issue but not recognised as distribution to owners per share (in CAD per share)

$ 0.293750

Dividends proposed or declared before financial statements authorised for issue but not recognised as distribution to owners

$ 2

Major preference share transactions | Series 5 preferred share

Disclosure of classes of share capital [line items]

Dividends proposed or declared before financial statements authorised for issue but not recognised as distribution to owners per share (in CAD per share)

$ 0.312500

Dividends proposed or declared before financial statements authorised for issue but not recognised as distribution to owners

$ 3

Major preference share transactions | Series 7 preferred share

Disclosure of classes of share capital [line items]

Dividends proposed or declared before financial statements authorised for issue but not recognised as distribution to owners per share (in CAD per share)

$ 0.281250

Dividends proposed or declared before financial statements authorised for issue but not recognised as distribution to owners

$ 3

Major preference share transactions | Series 9 preferred share

Disclosure of classes of share capital [line items]

Dividends proposed or declared before financial statements authorised for issue but not recognised as distribution to owners per share (in CAD per share)

$ 0.296875

Dividends proposed or declared before financial statements authorised for issue but not recognised as distribution to owners

$ 2

Major preference share transactions | Series 11 preferred share

Disclosure of classes of share capital [line items]

Dividends proposed or declared before financial statements authorised for issue but not recognised as distribution to owners per share (in CAD per share)

$ 0.359375

Dividends proposed or declared before financial statements authorised for issue but not recognised as distribution to owners

$ 2

Major preference share transactions | Series 13 preferred share

Disclosure of classes of share capital [line items]

Dividends proposed or declared before financial statements authorised for issue but not recognised as distribution to owners per share (in CAD per share)

$ 0.359375

Dividends proposed or declared before financial statements authorised for issue but not recognised as distribution to owners

$ 4

Major preference share transactions | Series 15 preferred share

Disclosure of classes of share capital [line items]

Dividends proposed or declared before financial statements authorised for issue but not recognised as distribution to owners per share (in CAD per share)

$ 0.279000

Dividends proposed or declared before financial statements authorised for issue but not recognised as distribution to owners

$ 2

Major preference share transactions | Series 17 preferred share

Disclosure of classes of share capital [line items]

Dividends proposed or declared before financial statements authorised for issue but not recognised as distribution to owners per share (in CAD per share)

$ 0.312500

Dividends proposed or declared before financial statements authorised for issue but not recognised as distribution to owners

$ 2

Major preference share transactions | Series 19 preferred share

Disclosure of classes of share capital [line items]

Dividends proposed or declared before financial statements authorised for issue but not recognised as distribution to owners per share (in CAD per share)

$ 0.312500

Dividends proposed or declared before financial statements authorised for issue but not recognised as distribution to owners

$ 3

Major preference share transactions | Series 21 preferred share

Disclosure of classes of share capital [line items]

Dividends proposed or declared before financial statements authorised for issue but not recognised as distribution to owners per share (in CAD per share)

$ 0.306250

Dividends proposed or declared before financial statements authorised for issue but not recognised as distribution to owners

$ 5