Debt Obligations - Summary (Details) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Debt Obligations
Applicable Interest Rate (as a percent)		4.22%	4.22%
Borrowings			$ 207,900,000	$ 116,200,000	$ 213,000,000
Outstanding Balance		$ 693,388,000	693,388,000	645,029,000
Available for borrowing		$ 527,600,000	527,600,000	581,833,000
Principal payments on senior unsecured notes			33,667,000	38,166,000	31,167,000
Proceeds from debt			$ 100,000,000		100,000,000
Bank Borrowings
Debt Obligations
Applicable Interest Rate (as a percent)		3.14%	3.14%
Borrowings			$ 107,900,000	116,200,000	113,000,000
Outstanding Balance		$ 93,900,000	93,900,000	112,000,000
Available for borrowing		$ 506,100,000	$ 506,100,000	488,000,000
Bank Borrowings | Subsequent Event
Debt Obligations
Borrowings	$ 18,000,000
Outstanding Balance	111,900,000
Available for borrowing	$ 488,100,000
Senior Unsecured Notes
Debt Obligations
Applicable Interest Rate (as a percent)		4.39%	4.39%
Borrowings		$ 100,000,000	$ 100,000,000		$ 100,000,000
Outstanding Balance		599,488,000	599,488,000	533,029,000
Available for borrowing		21,500,000	21,500,000	$ 93,833,000
$100,000 unsecured notes
Debt Obligations
Mezzanine loan principal amount		$ 100,000,000	$ 100,000,000
Interest rate (as a percent)		3.85%