17 property, plant and equipment


		Owned assets												Right-of-use lease assets (Note 19)
				Buildings and
		Network		leasehold						Assets under				Network		Real
(millions)	Note	assets		improvements		Other		Land		construction		Total		assets		estate		Other		Total		Total
AT COST
As at January 1, 2020		$	31,713	$	3,314	$	1,373	$	48	$	421	$	36,869	$	219	$	1,267	$	60	$	1,546	$	38,415
Additions			393		15		24		5		666		1,103		54		131		7		192		1,295
Additions arising from business acquisitions	18(b )		4		12		7		—		—		23		—		41		1		42		65
Dispositions, retirements and other			(379)		1		(122)		—		—		(500)		1		(24)		(9)		(32)		(532)
Assets under construction put into service			263		39		55		—		(357)		—		—		—		—		—		—
Net foreign exchange differences			2		5		9		—		—		16		—		13		—		13		29
As at June 30,2020		$	31,996	$	3,386	$	1,346	$	53	$	730	$	37,511	$	274	$	1,428	$	59	$	1,761	$	39,272
ACCUMULATED DEPRECIATION
As at January 1, 2020		$	21,060	$	2,052	$	875	$	—	$	—	$	23,987	$	6	$	174	$	16	$	196	$	24,183
Depreciation 1			767		62		75		—		—		904		14		101		9		124		1,028
Dispositions, retirements and other			(387)		(10)		(106)		—		—		(503)		—		(3)		(3)		(6)		(509)
Net foreign exchange differences			1		2		6		—		—		9		—		2		—		2		11
As at June 30, 2020		$	21,441	$	2,106	$	850	$	—	$	—	$	24,397	$	20	$	274	$	22	$	316	$	24,713
NET BOOK VALUE
As at December 31, 2019		$	10,653	$	1,262	$	498	$	48	$	421	$	12,882	$	213	$	1,093	$	44	$	1,350	$	14,232
As at June 30, 2020		$	10,555	$	1,280	$	496	$	53	$	730	$	13,114	$	254	$	1,154	$	37	$	1,445	$	14,559

(1)

For the six-month period ended June 30, 2020, depreciation includes $5 in respect of impairment of real estate right-of-use lease assets.

As at June 30, 2020, our contractual commitments for the acquisition of property, plant and equipment totalled $205 million over a period ending December 31, 2022 (December 31, 2019 – $136 million over a period ending December 31, 2022).