Fair Value Measurements - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Nov. 27, 2019	Jun. 27, 2012	Aug. 25, 2010
$250 Million Senior Notes | Senior Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt instrument, face amount	$ 250,000,000	$ 250,000,000			$ 250,000,000
Debt instrument, fair value		257,000,000.0
$400 Million Senior Notes | Senior Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt instrument, face amount	400,000,000	400,000,000		$ 400,000,000
$400 Million Senior Note | Senior Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt instrument, face amount		400,000,000	$ 400,000,000
Debt instrument, fair value	403,400,000
Fair Value, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, transfer in and out	0	0
Fair Value, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, transfer in and out	0	0
Fair Value, Level 2 | $250 Million Senior Notes | Senior Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt instrument, face amount					$ 250,000,000
Fair Value, Level 2 | $400 Million Senior Notes | Senior Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt instrument, face amount				$ 400,000,000
Debt instrument, fair value	432,000,000.0	415,700,000
Fair Value, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, transfer in and out	$ 0	$ 0