Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2017

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Summary of nonvested Common Share and nonvested Common Share unit activity

The following table summarizes nonvested common share and nonvested common share unit activity for the three months ended March 31, 2017:

	Time and Performance- Based Share Awards				Time-Based Share Awards				Share Units
(Shares in thousands)	Number of Shares		Weighted Average Grant Date Fair Value		Number of Shares		Weighted Average Grant Date Fair Value		Number of Share Units		Weighted Average Grant Date Fair Value
Outstanding at beginning of year	1,503		$	15.41	605		$	16.32	493		$	19.24
Granted	140		36.29		91		36.29		366		33.21
Vested	(48	)	22.48		(264	)	16.56		(253	)	18.40
Forfeited	—		N/A		—		N/A		(8	)	28.53
Outstanding at March 31, 2017	1,595		$	17.03	432		$	20.35	598		$	28.02

Schedule of portion of nonvested Common Shares earned based upon achievement of compounded annual book value per share growth

The portion of the nonvested performance-based share awards that will be earned based upon the achievement of compounded annual book value per share growth is as follows:

Performance level	Compounded Annual Book Value Per Share Growth		Nonvested Common Shares Earned
	<16	%	0	%
Threshold	16	%	25	%
	17	%	50	%
	18	%	75	%
Maximum	≥19	%	100	%

Schedule of compensation expense, net of forfeitures, and related tax effects recognized in connection with nonvested shares

Compensation expense, net of forfeitures, and related tax effects recognized in connection with nonvested shares was as follows:

	Three Months Ended March 31,
(In thousands)	2017		2016
Compensation expense	$	4,619	$	3,782
Income tax benefit	1,483		1,212