The following summarizes our principal contractual commitments, excluding open orders for purchases that support normal operations, as of December 31, 2016 (in millions):



	Year Ended December 31,
	2017		2018		2019		2020		2021		Thereafter		Total
Debt principal and interest	$	1,343	$	312	$	1,551	$	463	$	1,246	$	7,911	$	12,826
Capital lease obligations, including interest (1)	3,910		3,008		1,662		411		190		225		9,406
Finance lease obligations, including interest (2)	234		244		247		250		252		2,006		3,233
Operating leases	1,317		1,231		1,106		1,030		896		3,930		9,510
Unconditional purchase obligations (3)	655		590		303		96		43		23		1,710
Other commitments (4) (5)	1,025		824		621		493		365		3,071		6,399
Total commitments	$	8,484	$	6,209	$	5,490	$	2,743	$	2,992	$	17,166	$	43,084

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(1)	Excluding interest, current capital lease obligations of $3.0 billion and $4.0 billion are recorded within “Accrued expenses and other” as of December 31, 2015 and 2016, and $4.2 billion and $5.1 billion are recorded within “Other long-term liabilities” as of December 31, 2015 and 2016.


(2)	Excluding interest, current finance lease obligations of $99 million and $144 million are recorded within “Accrued expenses and other” as of December 31, 2015 and 2016, and $1.7 billion and $2.4 billion are recorded within “Other long-term liabilities and other” as of December 31, 2015 and 2016.

(3)

Includes unconditional purchase obligations related to long-term agreements to acquire and license digital media content that are not reflected on the consolidated balance sheets. For those agreements with variable terms, we do not estimate the total obligation beyond any minimum quantities and/or pricing as of the reporting date. Purchase obligations associated with renewal provisions solely at the option of the content provider are included to the extent such commitments are fixed or a minimum amount is specified.


(4)	Includes the estimated timing and amounts of payments for rent and tenant improvements associated with build-to-suit lease arrangements and equipment lease arrangements that have not been placed in service and digital media content liabilities associated with long-term digital media content assets with initial terms greater than one year.


(5)	Excludes $1.7 billion of accrued tax contingencies for which we cannot make a reasonably reliable estimate of the amount and period of payment, if any.