Shareholders' Equity - Dividends Declared (Details) - USD ($) $ / shares in Units, $ in Millions	Oct. 14, 2019	Jul. 09, 2019	Apr. 03, 2019	Feb. 04, 2019	Oct. 15, 2018	Jul. 10, 2018	Apr. 11, 2018	Feb. 05, 2018	Oct. 12, 2017	Jul. 10, 2017	Apr. 25, 2017	Feb. 06, 2017
Dividends Payable [Line Items]
Distribution Per Share (in dollars per share)	$ 0.48
Aggregate Payment Amount	$ 58.2
Dividend Paid
Dividends Payable [Line Items]
Distribution Per Share (in dollars per share)		$ 0.48	$ 0.48	$ 0.48	$ 0.47	$ 0.47	$ 0.47	$ 0.47	$ 0.47	$ 0.47	$ 0.47	$ 0.47
Aggregate Payment Amount		$ 58.2	$ 58.2	$ 57.9	$ 57.2	$ 57.2	$ 57.4	$ 58.3	$ 58.3	$ 58.3	$ 58.4	$ 52.5
Dividend Paid | Qualified
Dividends Payable [Line Items]
Distribution Per Share (in dollars per share)	$ 0	$ 0	$ 0	$ 0	$ 0.0461171	$ 0.0461171	$ 0.0461171	$ 0.0461171	$ 0.0176751	$ 0.0176751	$ 0.0176751	$ 0.0175622
Dividend Paid | Non-Qualified
Dividends Payable [Line Items]
Distribution Per Share (in dollars per share)	0.2759699	0.2759699	0.2759699	0.2759699	0.2090220	0.2090220	0.2090220	0.2090220	0.2484259	0.2484259	0.2484259	0.2468402
Dividend Paid | Nondividend Distributions
Dividends Payable [Line Items]
Distribution Per Share (in dollars per share)	$ 0.2040301	$ 0.2040301	$ 0.2040301	$ 0.2040301	$ 0.2148609	$ 0.2148609	$ 0.2148609	$ 0.2148609	$ 0.2038990	$ 0.2038990	$ 0.2038990	$ 0.2025975