Debt - Additional Information (Details)	1 Months Ended	3 Months Ended	6 Months Ended	12 Months Ended
	Oct. 31, 2014 USD ($)	Mar. 31, 2020 USD ($) derivative_instrument	Jun. 30, 2020 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2019 USD ($)	Feb. 28, 2018 USD ($)	Nov. 30, 2014 USD ($)
Line of Credit Facility [Line Items]
Document Period End Date			Jun. 30, 2020
Maximum capitalization ratio			55.00%
Number of instruments held | derivative_instrument		2
Interest rate swap principal		$ 200,000,000	$ 200,000,000			$ 200,000,000
Deferred Finance Costs, Own-share Lending Arrangement, Issuance Costs, Adjustment		$ 13,000,000
Deferred Finance Costs, Own-share Lending Arrangement, Issuance Costs, Accumulated Amortization			$ 700,000
Payments of financing costs				$ 3,000,000.0
Minimum [Member]
Line of Credit Facility [Line Items]
Commitment fee percentage			0.125%
Maximum [Member]
Line of Credit Facility [Line Items]
Commitment fee percentage			0.30%
Senior Notes due 2024 [Member]
Line of Credit Facility [Line Items]
Senior notes			$ 500,000,000			$ 500,000,000		$ 500,000,000
Interest rate, stated percentage			4.65%			4.65%		4.65%
Fixed interest rate		4.65%
Derivative Liability, Notional Amount		$ 100,000,000
Payments of debt issuance costs					$ 6,900,000
Senior Notes due 2028 [Member]
Line of Credit Facility [Line Items]
Senior notes			$ 300,000,000			$ 300,000,000	$ 300,000,000
Interest rate, stated percentage			6.00%			6.00%	6.00%
Payments of debt issuance costs				$ 4,200,000
Line of Credit [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 500,000,000
Debt instrument, term	5 years
Available additional borrowing capacity	$ 300,000,000
Face amount	$ 300,000,000
Percent of commitments affected by amendment							90.00%
Line of Credit [Member] | October 25, 2021 [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity							$ 500,000,000
Line of Credit [Member] | January 25, 2023 [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity							$ 450,000,000
Credit Agreement [Member] | Applicable Margin [Member] | Minimum [Member] | Adjusted Base Rate Advances [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate			0.125%
Credit Agreement [Member] | Applicable Margin [Member] | Minimum [Member] | Eurodollar Advances [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate			1.125%
Credit Agreement [Member] | Applicable Margin [Member] | Maximum [Member] | Adjusted Base Rate Advances [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate			0.75%
Credit Agreement [Member] | Applicable Margin [Member] | Maximum [Member] | Eurodollar Advances [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate			1.75%
Credit Agreement [Member] | Adjusted Base Rate [Member] | Minimum [Member] | Adjusted Base Rate Advances [Member] | Federal Funds Rate [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate			0.50%
Credit Agreement [Member] | Adjusted Base Rate [Member] | Minimum [Member] | Adjusted Base Rate Advances [Member] | Eurodollar Rate [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate			1.00%