Basis of Presentation and Summary of Significant Accounting Policies - Carrying Amounts and Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Assets
Money market funds	$ 107,403	$ 115,769
Marketable securities – certificates of deposit	67,200	67,637
Marketable securities – equity securities	120,006	58
Total assets	294,609	183,464
Liabilities
Interest rate swaps	1,195
Total liabilities	1,195
Level 1
Assets
Money market funds	107,403	115,769
Marketable securities – certificates of deposit	67,200	67,637
Marketable securities – equity securities	120,006	58
Total assets	294,609	183,464
Liabilities
Interest rate swaps	0
Total liabilities	0
Level 2
Assets
Money market funds	0	0
Marketable securities – certificates of deposit	0	0
Marketable securities – equity securities	0	0
Total assets	0	0
Liabilities
Interest rate swaps	1,195
Total liabilities	1,195
Level 3
Assets
Money market funds	0	0
Marketable securities – certificates of deposit	0	0
Marketable securities – equity securities	0	0
Total assets	0	$ 0
Liabilities
Interest rate swaps	0
Total liabilities	$ 0