Stock-Based Compensation Plans (Tables)

6 Months Ended

Jun. 30, 2020

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Summary of Stock Option Activity

A summary of stock option activity is as follows:

	Number of Shares	Weighted Average Exercise Price ($)		Weighted Average Remaining Contractual Term (Years)	Aggregate Intrinsic Value of In-the-Money Options ($)
Outstanding as of December 31, 2019	4,006,816	$	18.18
Exercised	(1,110,583)	19.58
Forfeited	(57,744)	19.08
Expired	(6,090)	18.44
Outstanding as of June 30, 2020	2,832,399	$	17.61	3.98	$	26,562,039
Exercisable as of June 30, 2020	2,685,163	$	17.48	4.11	$	25,532,991

LTIP Performance Shares

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Summary of Nonvested Performance Award Activity

A summary of nonvested long-term incentive program performance share awards (“LTIP performance shares”) is as follows:

	Number of Shares at Expected Attainment	Weighted Average Grant Date Fair Value
Nonvested as of December 31, 2019	669,469	$	20.12
Vested	(668,240)	20.12
Forfeited	(5,368)	20.12
Change in attainment	4,139	20.12
Nonvested as of June 30, 2020	—	$	—

Restricted Share Awards (RSAs)

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Summary of Nonvested Restricted Share Award Activity

A summary of nonvested restricted share awards (“RSAs”) is as follows:

	Number of Shares	Weighted Average Grant Date Fair Value
Nonvested as of December 31, 2019	92,842	$	20.13
Vested	(88,913)	20.12
Forfeited	(3,929)	20.35
Nonvested as of June 30, 2020	—	$	—

Total Shareholder Return Awards (TSRs)

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Summary of Nonvested Performance Award Activity

A summary of nonvested TSRs is as follows:

	Number of Shares	Weighted Average Grant Date Fair Value
Nonvested as of December 31, 2019	1,062,291	$	35.77
Granted	677,195	30.01
Vested	(199,413)	24.37
Forfeited	(79,246)	39.41
Change in payout rate	(14,259)	24.37
Nonvested as of June 30, 2020	1,446,568	$	34.56

Total Shareholder Return Awards (TSRs) | Monte Carlo Simulation Model

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Summary of Grant Date Fair Value Weighted-Average Assumptions, Awards Other Than Options

The fair value of TSRs granted during the six months ended June 30, 2020 and 2019, were estimated on the date of grant using the Monte Carlo simulation model, acceptable under ASC 718, using the following weighted average assumptions:

	Six Months Ended June 30,
	2020		2019
Expected life (years)	2.8		2.8
Risk-free interest rate	0.5	%	2.5	%
Expected volatility	31.4	%	29.3	%
Expected dividend yield	—		—

Restricted Share Units (RSUs)

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Summary of Nonvested Restricted Share Unit Activity

A summary of nonvested RSUs is as follows:

	Number of Shares	Weighted Average Grant Date Fair Value
Nonvested as of December 31, 2019	1,009,404	$	29.96
Granted	787,871	25.65
Vested	(399,605)	29.14
Forfeited	(114,303)	29.68
Nonvested as of June 30, 2020	1,283,367	$	27.59