Stockholders' Equity (Narrative) (Details) - USD ($)			3 Months Ended						9 Months Ended
	Jul. 18, 2023	Apr. 26, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Oct. 31, 2021
Class of Stock [Line Items]
Preferred stock, shares authorized (in shares)			10,000,000						10,000,000		10,000,000
Stockholders' equity			$ 11,847,200,000	$ 11,635,700,000	$ 11,587,800,000	$ 11,030,400,000	$ 11,069,700,000	$ 11,409,800,000	$ 11,847,200,000	$ 11,030,400,000	$ 11,259,500,000	$ 12,016,800,000
Common stock dividends (in usd per share)			$ 0.75	$ 0.75	$ 0.75	$ 0.75	$ 0.70	$ 0.70
Stock repurchase program, number of shares authorized to be repurchased (in shares)													25,000,000
Stock repurchase, shares (in shares)			14,738			11,080			2,426,793	309,334
Stock repurchase, aggregate cost			$ 1,100,000	$ 99,300,000	$ 100,900,000	$ 1,200,000	$ 300,000	$ 33,800,000	$ 201,300,000	$ 35,200,000
Share-based payment arrangement, shares withheld for tax withholding obligation (in shares)									356,145
Average price paid per share for common stock repurchased (in usd per share)			$ 77.39			$ 96.43			$ 82.95	$ 113.89
Preferred Stock
Class of Stock [Line Items]
Stockholders' equity			$ 884,900,000	$ 884,900,000	$ 884,900,000	$ 884,900,000	$ 884,900,000	$ 884,900,000	$ 884,900,000	$ 884,900,000	$ 884,900,000	$ 884,900,000
Series D Preferred Stock
Class of Stock [Line Items]
Preferred stock, outstanding (in shares)			5,000						5,000		5,000
Preferred stock, without par value (in dollars per share)			$ 0						$ 0
Preferred stock, liquidation preference			$ 100,000						$ 100,000
Depository shares, liquidation preference per share (in dollars per share)			$ 1,000						$ 1,000
Preferred stock, annual dividend rate									4.60%
Preferred stock, dividend payment rate, variable rate									3.202%
Common stock dividends (in usd per share)	$ 2,300
Series D Preferred Stock | Preferred Stock
Class of Stock [Line Items]
Stockholders' equity			$ 493,500,000						$ 493,500,000		$ 493,500,000
Series E Preferred Stock
Class of Stock [Line Items]
Preferred stock, outstanding (in shares)			16,000						16,000		16,000
Percentage of ownership interest per each depository shares			0.10%						0.10%
Preferred stock, without par value (in dollars per share)			$ 0						$ 0
Preferred stock, liquidation preference			$ 25,000						$ 25,000
Depository shares, liquidation preference per share (in dollars per share)			$ 25						$ 25
Preferred stock, annual dividend rate									4.70%
Common stock dividends (in usd per share)		$ 293.75
Series E Preferred Stock | Preferred Stock
Class of Stock [Line Items]
Stockholders' equity			$ 391,400,000						$ 391,400,000		$ 391,400,000
Series D Preferred Stock, Depositary Shares
Class of Stock [Line Items]
Preferred stock, outstanding (in shares)			500,000						500,000
Preferred stock, shares issued (in shares)			500,000						500,000
Percentage of ownership interest per each depository shares			1.00%						1.00%
Series E Preferred Stock Depositary Shares
Class of Stock [Line Items]
Preferred stock, outstanding (in shares)			16,000,000						16,000,000
Preferred stock, shares issued (in shares)			16,000,000						16,000,000