Equity and Capital Equity and Capital - Common Stock (Details) - USD ($)			6 Months Ended
	Feb. 05, 2019	Jan. 31, 2019	Jun. 30, 2019	Jun. 30, 2018
Class of Stock [Line Items]
Common stock remaining available for Issuance			500,000,000
Stock Repurchased and Retired During Period, Value			$ (32,778,000)	$ (124,989,000)
Stock Repurchase Program, Authorized Amount	$ 250,000,000
Stock Repurchase Program Expiration Date	Feb. 04, 2020
Common Stock [Member]
Class of Stock [Line Items]
Stock Repurchased and Retired During Period, Shares		563,229
Stock Repurchased and Retired During Period, Value		$ (32,800,000)	(6,000)	$ (21,000)
Common Stock [Member] | Average share price [Member]
Class of Stock [Line Items]
Stock Repurchased and Retired During Period, Value Per Share		$ (58.17)
Accumulated Other Comprehensive Income (Loss) [Member] | Common Stock [Member]
Class of Stock [Line Items]
Stock Repurchased and Retired During Period, Value			$ 0
ATM Equity Offering Program [Member]
Class of Stock [Line Items]
Shares issued under program			0	0
Maximum [Member]
Class of Stock [Line Items]
Equity Issuances, Common Shares Authorized for Issuance			500,000,000