Summary of Significant Accounting Policies - Additional Information (Details) $ in Thousands		3 Months Ended		9 Months Ended
	Sep. 01, 2020 USD ($)	Sep. 30, 2020 USD ($) shares	Sep. 30, 2019 shares	Sep. 30, 2020 USD ($) shares	Sep. 30, 2019 shares	Sep. 03, 2020 USD ($)	Mar. 30, 2020 TelevisionStation	Dec. 31, 2019 USD ($)
Significant Accounting Policies [Line Items]
Unrestricted cash on hand		$ 409,906		$ 409,906				$ 232,070
Working capital		$ 669,500		$ 669,500				404,200
Stock options and restricted stock units with potentially dilutive effect (in shares) | shares		85,000	2,700	157,000	10,900
Bad debt expense		$ 14,400		$ 24,700
Accounts receivable, allowance for doubtful accounts		29,082		29,082				$ 17,205
Allowance for uncollectable doubtful accounts other noncurrent		$ 13,100		$ 13,100
Accounting Standards Update 2019-04 [Member]
Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adopted [true false]		true		true
Change in accounting principle, accounting standards update, adoption date		Jan. 01, 2020		Jan. 01, 2020
Change in accounting principle, accounting standards update, immaterial effect [true false]		true		true
Accounting Standards Update 2019-02 [Member]
Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adopted [true false]		true		true
Change in accounting principle, accounting standards update, adoption date		Jan. 01, 2020		Jan. 01, 2020
Change in accounting principle, accounting standards update, immaterial effect [true false]		true		true
Accounting Standards Update 2018-17 [Member]
Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adopted [true false]		true		true
Change in accounting principle, accounting standards update, adoption date		Jan. 01, 2020		Jan. 01, 2020
Change in accounting principle, accounting standards update, immaterial effect [true false]		true		true
Accounting Standards Update 2018-13 [Member]
Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adopted [true false]		true		true
Change in accounting principle, accounting standards update, adoption date		Jan. 01, 2020		Jan. 01, 2020
Change in accounting principle, accounting standards update, immaterial effect [true false]		true		true
Accounting Standards Update 2018-14 [Member]
Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adopted [true false]		true		true
Change in accounting principle, accounting standards update, adoption date		Jan. 01, 2020		Jan. 01, 2020
Change in accounting principle, accounting standards update, immaterial effect [true false]		true		true
Accounting Standards Update 2016-13 [Member]
Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adopted [true false]		true		true
Change in accounting principle, accounting standards update, adoption date		Jan. 01, 2020		Jan. 01, 2020
Change in accounting principle, accounting standards update, immaterial effect [true false]		true		true
Revolving loans [Member]
Significant Accounting Policies [Line Items]
Line of credit facility, maturity period				2023-10
Nexstar [Member] | Revolving loans [Member]
Significant Accounting Policies [Line Items]
Available borrowing capacity		$ 172,700		$ 172,700		$ 139,700
Mission [Member] | Marshall Broadcasting Group, Inc [Member] | Asset Purchase Agreement [Member]
Significant Accounting Policies [Line Items]
Number of television stations owned | TelevisionStation							3
Purchase price	$ 53,200
Purchase price settled against existing loans receivable	49,000
Cash payment	$ 4,200
Mission [Member] | Revolving loans [Member]
Significant Accounting Policies [Line Items]
Available borrowing capacity		$ 25,000		$ 25,000