Stockholders' Deficit - Narrative (Details) - USD ($)			3 Months Ended			9 Months Ended		12 Months Ended
	Apr. 03, 2020	Jan. 10, 2020	Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Feb. 20, 2019
Equity, Class of Treasury Stock [Line Items]
Dividends paid on common stock						$ 23,934,000	$ 35,273,000
Dividends declared per common share (USD per share)			$ 0	$ 0.76	$ 0.69	$ 0.76	$ 2.07	$ 0.69
Dividends paid per common share (USD per share)	$ 0.76	$ 0.69	$ 0		$ 0.69	$ 1.45	$ 2.01
Treasury stock reissued (shares)						396,996
Reissuance of treasury stock			$ 0		$ 3,733,000	$ 20,523,000	$ 10,671,000
Treasury Stock
Equity, Class of Treasury Stock [Line Items]
Treasury stock reissued (shares)			16,000		73,000	397,000	260,000
Reissuance of treasury stock			$ 709,000		$ 3,151,000	$ 17,865,000	$ 11,408,000
Common Stock
Equity, Class of Treasury Stock [Line Items]
Treasury stock reissued (shares)			16,000		73,000	397,000	260,000
Reissuance of treasury stock							$ (1,000)
2019 Repurchase Program
Equity, Class of Treasury Stock [Line Items]
Stock repurchase program, authorized amount									$ 200,000,000