Shareholders' Equity - Stock Buyback Program (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jun. 12, 2019	Feb. 14, 2018
Equity, Class of Treasury Stock [Line Items]
Purchase of treasury shares	$ 0	$ 95,175,000	$ 0
Common Stock | February 2018 Stock Buyback Program
Equity, Class of Treasury Stock [Line Items]
Stock repurchase program, authorized amount					$ 200,000,000
Purchase of treasury shares (in shares)		4,210,254
Purchase of treasury shares		$ 95,200,000
Amended Credit Agreement
Equity, Class of Treasury Stock [Line Items]
Maximum borrowing capacity	$ 100,000,000.0
Line of Credit | Revolving Credit Facility | Amended Credit Agreement
Equity, Class of Treasury Stock [Line Items]
Maximum borrowing capacity				$ 900,000,000.0	$ 900,000,000