	As of March 31, 2019			As of December 31, 2018
Revolving credit facility(A)	$	37,802		$	28,059
Term loan		200,000			200,000
4.000% Senior Unsecured Notes due 2022(B)		560,900			573,350
5.500% Senior Unsecured Notes due 2024		300,000			300,000
6.375% Senior Unsecured Notes due 2024		500,000			500,000
3.325% Senior Unsecured Notes due 2025(B)		560,900			573,350
5.250% Senior Unsecured Notes due 2026		500,000			500,000
5.000% Senior Unsecured Notes due 2027		1,400,000			1,400,000
	$	4,059,602		$	4,074,759
Debt issue costs, net		(36,034	)		(37,370	)
	$	4,023,568		$	4,037,389

(A)	Includes £29 million and £22 million of GBP-denominated borrowings that reflect the exchange rate at March 31, 2019 and December 31, 2018, respectively.

(B)	These notes are Euro-denominated and reflect the exchange rate at March 31, 2019 and December 31, 2018, respectively.

As of March 31, 2019, principal payments due on our debt (which exclude the effects of any discounts, premiums, or debt issue costs recorded) are as follows (in thousands):

2019	$	—
2020		—
2021		37,802
2022		760,900
2023		—
Thereafter		3,260,900
Total	$	4,059,602

Our debt facilities impose certain restrictions on us, including restrictions on our ability to: incur debts; create or incur liens; provide guarantees in respect of obligations of any other entity; make redemptions and repurchases of our capital stock; prepay, redeem or repurchase debt; engage in mergers or consolidations; enter into affiliated transactions; dispose of real estate or other assets; and change our business. In addition, the credit agreements governing our revolving credit and term loan agreement (“Credit Facility”) limit the amount of dividends we can pay as a percentage of normalized adjusted funds from operations, as defined in the agreements, on a rolling four quarter basis. At March 31, 2019, the dividend restriction was 95% of normalized adjusted funds from operations (“NAFFO”). The indentures governing our senior unsecured notes also limit the amount of dividends we can pay based on the sum of 95% of NAFFO, proceeds of equity issuances and certain other net cash proceeds. Finally, our senior unsecured notes require us to maintain total unencumbered assets (as defined in the related indenture) of not less than 150% of our unsecured indebtedness.

In addition to these restrictions, the Credit Facility contains customary financial and operating covenants, including covenants relating to our total leverage ratio, fixed charge coverage ratio, secured leverage ratio, consolidated adjusted net worth, unsecured leverage ratio, and unsecured interest coverage ratio. The Credit Facility also contains customary events of default, including among others, nonpayment of principal or interest, material inaccuracy of representations and failure to comply with our covenants. If an event of default occurs and is continuing under the Credit Facility, the entire outstanding balance may become immediately due and payable. At March 31, 2019, we were in compliance with all such financial and operating covenants.