Earnings per Common Share (Tables)

12 Months Ended

Dec. 31, 2018

Earnings Per Share [Abstract]

Net Income, Weighted Average Common Shares Used In Calculating Basic Earnings Per Common Share And Diluted EPS

	Years Ended December 31,
	2018			2017			2016
Numerator
Net income attributable to stockholders	$	251.0		$	519.6		$	565.4
Less: Preferred stock dividends	(14.2		)	—			—
Net income attributable to common stockholders	236.8			519.6			565.4
Less: Common stock dividends paid	(133.8		)	(119.0		)	(125.4		)
Undistributed earnings	$	103.0		$	400.6		$	440.0
Denominator
Weighted average common shares outstanding used in basic earnings per common share calculations	59,239,608			54,986,654			61,261,288
Incremental common shares from:
PSUs	260,904			284,835			632,731
ESPP	45,012			39,543			40,755
MCPS	—			—			—
Weighted average common shares used in diluted earnings per common share calculations	59,545,524			55,311,032			61,934,774
Earnings per common share – Basic
Distributed earnings	$	2.26		$	2.16		$	2.05
Undistributed earnings	1.74			7.29			7.18
Net income attributable to common stockholders	$	4.00		$	9.45		$	9.23
Earnings per common share – Diluted
Distributed earnings	$	2.25		$	2.15		$	2.03
Undistributed earnings	1.73			7.24			7.10
Net income attributable to common stockholders	$	3.98		$	9.39		$	9.13