Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2014

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

Summary of Company's Option Activity

A summary of the Company’s option activity and related information for the three years ended December 31, 2014 is as follows:

	Number of options			Weighted- average price		Weighted- average remaining contractual term (in years)		Aggregate intrinsic value (in millions)
Balance at December 31, 2011		3,086,019		$	23.52
Options granted		128,500			29.63
Options exercised		(327,498	)		17.95
Options cancelled/forfeited/expired		(48,468	)		27.63
Balance at December 31, 2012		2,838,553			24.37
Options granted		192,800			29.14
Options exercised		(1,237,341	)		24.71
Options cancelled/forfeited/expired		(21,950	)		25.20
Balance at December 31, 2013		1,772,062			24.68
Options granted		203,600			32.79
Options exercised		(612,682	)		21.55
Options cancelled/forfeited/expired		(19,220	)		30.35
Balance at December 31, 2014		1,343,760		$	27.25		2.97	$	11.6
Exercisable at December 31, 2014		883,605		$	25.37		1.80	$	9.3
Expected to vest after December 31, 2014		414,140		$	30.68		5.22	$	2.1

Options Outstanding and Options Exercisable by Exercise Price with Weighted-Average Remaining Contractual Life for Options Outstanding and Weighted-Average Exercise Price

The following table indicates the options outstanding and options exercisable by exercise price with the weighted-average remaining contractual life for the options outstanding and the weighted-average exercise price at December 31, 2014:

	Options Outstanding						Options Exercisable
Exercise price	Number outstanding at December 31, 2014		Weighted- average remaining contractual life (Years)		Weighted- average grant date value		Number exercisable at December 31, 2014		Weighted- average grant date value
$15–20		149,700		1.17	$	15.62		149,700	$	15.62
20–25		229,225		1.79		23.19		212,040		23.18
25–30		653,435		2.56		29.12		510,465		29.24
30–35		302,000		5.56		32.35		10,400		32.40
35–40		9,400		5.96		37.83		1,000		38.89
$15–40		1,343,760		2.97	$	27.25		883,605	$	25.37

Schedule of Weighted-Average Assumptions Used to Determine Fair Value of Option Granted

The fair value of each option granted was estimated on the date of grant using the Black-Scholes option-pricing model using the following weighted-average assumptions:

	Year Ended December 31,
	2014			2013			2012
Expected term (in years)		5.0			5.0			5.0
Expected volatility		40.5	%		50.3	%		52.1	%
Expected dividend yields		3.0	%		3.3	%		3.2	%
Risk-free interest rates		1.5	%		0.8	%		0.8	%

Summary of Company's Restricted Stock Units Activity

The following table summarizes the activity of the Company’s RSUs, which includes service-based and performance-based awards, for the three years ended December 31, 2014:

	Number of shares			Weighted- average grant Date fair value		Aggregate intrinsic value (in millions)
Balance at December 31, 2011		187,810		$	26.33
RSUs granted		109,200			31.37
RSUs vested		(34,190	)		27.85
RSUs cancelled/forfeited/expired		—			—
Balance at December 31, 2012		262,820			28.22
RSUs granted		150,300			26.89
RSUs vested		(87,840	)		24.98
RSUs cancelled/forfeited/expired		(4,300	)		29.24
Balance at December 31, 2013		320,980			28.47
RSUs granted		118,864			30.85
RSUs vested		(120,721	)		27.30
RSUs cancelled/forfeited/expired		(7,540	)		30.34
Balance at December 31, 2014		311,583		$	29.78	$	11.2