We lease communications towers, ground, colocation, and dark fiber to tenants under operating leases. Our leases have initial lease terms ranging from less than one year to 35 years, most of which include options to extend or renew the leases for less than one year to 20 years (based on the satisfaction of certain conditions as defined in the lease agreements), and some of which may include options to terminate the leases within one to six months. Certain lease agreements contain provisions for future rent increases. Payments due under the lease contracts include fixed payments plus, for some of our leases, variable payments.

The components of lease income for the three and six months ended June 30, 2021 and 2020, respectively, are as follows:

	Three Months Ended June 30,				Six Months Ended June 30,
(Thousands)	2021		2020		2021		2020
Lease income - operating leases	$	206,124	$	197,432	$	411,319	$	393,976

Lease payments to be received under non-cancellable operating leases where we are the lessor for the remainder of the lease terms as of June 30, 2021 are as follows:

(Thousands)	June 30, 2021⁽¹⁾
2021	$	368,041
2022		751,516
2023		755,574
2024		757,431
2025		759,168
Thereafter		3,734,183
Total lease receivables	$	7,125,913
⁽¹⁾ Total future minimum lease payments to be received include $6.1 billion relating to the Windstream Leases.

The underlying assets under operating leases where we are the lessor are summarized as follows:

(Thousands)	June 30, 2021			December 31, 2020
Land	$	26,596		$	26,596
Building and improvements		340,096			335,495
Poles		273,934			266,758
Fiber		3,147,976			2,994,465
Equipment		428			421
Copper		3,902,265			3,850,988
Conduit		89,960			89,773
Tower assets		1,397			1,397
Finance lease assets		28,126			32,660
Other assets		10,643			10,425
		7,821,421			7,608,978
Less: accumulated depreciation		(5,319,033	)		(5,222,731	)
Underlying assets under operating leases, net	$	2,502,388		$	2,386,247

Depreciation expense for the underlying assets under operating leases where we are the lessor for the three and six months ended June 30, 2021 and 2020, respectively, is summarized as follows:

	Three Months Ended June 30,				Six Months Ended June 30,
(Thousands)	2021		2020		2021		2020
Depreciation expense for underlying assets under operating leases	$	44,107	$	53,303	$	90,020	$	109,437

We have commitments under operating leases for communications towers, ground, colocation, dark fiber lease arrangements, and buildings. We also have finance leases for dark fiber lease arrangements and other communications equipment. Our leases have initial lease terms ranging from less than one year to 30 years, most of which include options to extend or renew the leases for less than one year to 20 years, and some of which may include options to terminate the leases within one to six months. Certain lease agreements contain provisions for future rent increases. Payments due under the lease contracts include fixed payments plus, for some of our leases, variable payments.

As of June 30, 2021, we have short term lease commitments amounting to approximately $2.6 million.

The components of lease cost for the three and six months ended June 30, 2021 and 2020, respectively, are as follows:

	Three Months Ended June 30,						Six Months Ended June 30,
(Thousands)	2021			2020			2021			2020
Finance lease cost
Amortization of ROU assets	$	1,335		$	954		$	2,697		$	1,979
Interest on lease liabilities		717			969			1,627			1,957
Total finance lease cost		2,052			1,923			4,324			3,936
Operating lease cost		3,102			6,421			8,215			13,959
Short-term lease cost		748			526			1,440			1,009
Variable lease cost		109			66			296			84
Less sublease income		(3,246	)		(3,076	)		(6,228	)		(6,770	)
Total lease cost	$	2,765		$	5,860		$	8,047		$	12,218

Amounts reported in the Condensed Consolidated Balance Sheets for leases where we are the lessee were as follows:

(Thousands)	Location on Condensed Consolidated Balance Sheets	June 30, 2021			December 31, 2020
Operating leases
ROU assets, net	Other assets, net	$	73,620		$	97,850
Lease liabilities	Accounts payable, accrued expenses and other liabilities, net		49,909			71,483

Finance leases
ROU asset, gross	Property, plant and equipment, net	$	71,444		$	128,098
Lease liabilities	Finance lease obligations		14,497			48,724

Weighted-average remaining lease term
Operating leases		8.8 years			12.2 years
Finance leases		13.3 years			13.3 years

Weighted-average discount rate
Operating leases			9.5	%		9.9	%
Finance leases			11.0	%		8.0	%

Other information related to leases as of June 30, 2021 and 2020, respectively, are as follows:

(Thousands)	2021		2020
Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows from finance leases	$	1,627	$	1,957
Operating cash flows from operating leases		10,381		14,470
Financing cash flows from finance leases		1,393		1,979

Non-cash items:
New operating leases and remeasurements, net	$	1,722	$	3,847
New finance leases		-		31

Future lease payments under non-cancellable leases as of June 30, 2021 are as follows:

(Thousands)	Operating Leases			Finance Leases
2021	$	7,446		$	1,164
2022		12,672			2,225
2023		10,484			2,174
2024		8,064			1,972
2025		5,439			1,911
Thereafter		31,892			15,440
Total undiscounted lease payments	$	75,997		$	24,886
Less: imputed interest		(26,088	)		(10,389	)
Total lease liabilities	$	49,909		$	14,497

(Thousands)	Sublease Rentals
2021	$	4,458
2022		9,310
2023		9,377
2024		9,445
2025		9,513
Thereafter		136,177
Total	$	178,280