Debt Commitments

6 Months Ended

Jun. 30, 2020

Debt Disclosure [Abstract]

Debt Commitments

(7) Debt Commitments

Credit Facility, Notes Payable, and Commitments

Debt obligations and letters of credit outstanding at the end of each period consisted of the following:

	Average Interest Rate at June 30, 2020			Debt Outstanding
			Maturity Date	June 30, 2020		December 31, 2019
Unsecured revolving credit facility	1.10	%	November 30, 2023	$	—	210.0
Senior unsecured promissory notes payable, Series A	2.00	%	July 20, 2021	40.0		40.0
Senior unsecured promissory notes payable, Series B	2.45	%	July 20, 2022	35.0		35.0
Senior unsecured promissory notes payable, Series C	3.22	%	March 1, 2024	60.0		60.0
Senior unsecured promissory notes payable, Series D	2.66	%	May 15, 2025	75.0		—
Senior unsecured promissory notes payable, Series E	2.72	%	May 15, 2027	50.0		—
Senior unsecured promissory notes payable, Series F	1.69	%	June 24, 2023	70.0		—
Senior unsecured promissory notes payable, Series G	2.13	%	June 24, 2026	25.0		—
Senior unsecured promissory notes payable, Series H	2.50	%	June 24, 2030	50.0		—
Total				405.0		345.0
Less: Current portion of debt				—		(3.0	)
Long-term debt				$	405.0	342.0
Outstanding letters of credit under unsecured revolving credit facility - contingent obligation				$	36.3	36.3

Unsecured Revolving Credit Facility

We have a $700.0 committed unsecured revolving credit facility ('Credit Facility'). The Credit Facility includes a committed letter of credit subfacility of $55.0. Any borrowings outstanding under the Credit Facility for which we have the ability and intent to pay using cash within the next twelve months, will be classified as a current liability. The Credit Facility contains certain financial and other covenants, and our right to borrow under the Credit Facility is conditioned upon, among other things, our compliance with these covenants. We are currently in compliance with these covenants.

Borrowings under the Credit Facility generally bear interest at a rate per annum equal to the London Interbank Offered Rate ('LIBOR') for interest periods of various lengths selected by us, plus 0.95%. We pay a commitment fee for the unused portion of the Credit Facility. This fee is either 0.10% or 0.125% per annum based on our usage of the Credit Facility.

Senior Unsecured Promissory Notes Payable

We have issued senior unsecured promissory notes under our master note agreement (the 'Master Note Agreement') in the aggregate principal amount of $405.0. Our aggregate borrowing capacity under the Master Note Agreement is $600.0; however, none of the institutional investors party to that agreement are committed to purchase notes thereunder. There is no amortization of these notes prior to their maturity date and interest is payable quarterly. The notes currently issued under our Master Note Agreement, including the maturity date and fixed interest rate per annum of each series of note, are contained in the table above.