Equity - Additional Information (Details) - USD ($)	3 Months Ended	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Jun. 30, 2020	Feb. 28, 2018
Stockholders Equity Note [Line Items]
Net proceeds from issuance of common stock		$ 5,881,000	$ 450,710,000	$ 142,601,000
Direct stock purchase and dividend reinvestment plan			$ 6,307,000	1,706,000
Amount of shares repurchased during period		$ 21,659,000		$ 15,544,000
Share Repurchase Plan, February 2018
Stockholders Equity Note [Line Items]
Stock repurchase program, authorized amount						$ 100,000,000
Shares repurchased during period (in shares)		3,047,335
Amount of shares repurchased during period	$ 22,000,000
Stock repurchase program, remaining authorized repurchase amount	78,000,000	$ 78,000,000
Convertible debt securities
Stockholders Equity Note [Line Items]
Securities excluded in the calculation of diluted earnings per share		31,306,089
Equity awards
Stockholders Equity Note [Line Items]
Securities excluded in the calculation of diluted earnings per share		12,622	10,051	7,230
ATM Offerings | Common Stock
Stockholders Equity Note [Line Items]
Aggregate value of common stock issuable				$ 150,000,000	$ 175,000,000
Issuance of common stock (in shares)		129,500	2,259,758
Net proceeds from issuance of common stock		$ 2,000,000	$ 36,000,000
Outstanding for future offerings, amount	$ 110,000,000	$ 110,000,000
Common Stock
Stockholders Equity Note [Line Items]
Issuance of common stock (in shares)		350,088	28,724,645	8,738,319
Direct stock purchase and dividend reinvestment plan (in shares)		0	399,838	113,004
Direct stock purchase and dividend reinvestment plan			$ 4,000	$ 1,000
Shares repurchased during period (in shares)		3,047,335		1,040,829
Amount of shares repurchased during period		$ 30,000		$ 10,000