Equity-Based Compensation Plans (Tables)

12 Months Ended

Dec. 31, 2014

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

Employee Equity-Based Compensation Expense

Employee equity-based compensation expense was recognized as follows:

(In thousands)	2014		2013		2012
Restricted stock units	$	1,966	$	1,801	$	970
Performance shares	4,964		5,075		7,364
Stock options	1,254		—		—
Total employee equity-based compensation	$	8,184	$	6,876	$	8,334
Related tax benefit	$	2,955	$	2,049	$	2,886

Summary of Status of Outstanding RSU Awards

A summary of the status of outstanding unvested RSU awards as of December 31, 2014, 2013 and 2012, and changes during those years, is presented below:

	2014				2013				2012
	Shares		Weighted Average Grant Date Fair Value		Shares		Weighted Average Grant Date Fair Value		Shares		Weighted Average Grant Date Fair Value
Unvested shares outstanding at
January 1	102,658		$	39.85	63,727		$	35.57	169,344		$	11.33
Granted	31,567		66.33		72,702		43.44		52,294		34.59
Vested	(32,117	)	38.94		(30,190	)	39.21		(155,177	)	8.82
Forfeited	(8,854	)	52.28		(3,581	)	42.03		(2,734	)	34.07
Unvested shares outstanding at   December 31	93,254		47.95		102,658		39.85		63,727		35.57
Aggregate intrinsic value (in   thousands)			$	6,393			$	5,390			$	2,496

Schedule of Share-based Compensation, Activity [Table Text Block]

A summary of the status of outstanding stock option awards as of December 31, 2014, and changes during the year, is presented below:

	2014
	Shares		Weighted Average Grant Date Fair Value
Outstanding options at January 1	—		$	—
Granted	163,137		66.85
Forfeited	(12,557	)	66.97
Outstanding options at December 31	150,580		66.84
Aggregate intrinsic value (in thousands)			$	258

Assumption Used in Black-Scholes Option-Pricing Model to Estimate Fair Value of Stock Options

The fair value of performance share awards is estimated using a Monte Carlo simulation model. For performance shares granted in 2014, the following assumptions were used in our Monte Carlo model:

Closing price of stock on date of grant	$	66.97
Risk free rate	0.66		%
Measurement period	3 years
Volatility	30		%

The weighted-average fair value of stock options granted in 2014 on the grant date was estimated at $22.99 per option based on the following assumptions:

Volatility	30	%
Risk-free interest rate	2.05	%
Expected life-years	6.4

Summary of Status of Outstanding Performance Share Awards

A summary of the status of outstanding performance share awards as of December 31, 2014, 2013 and 2012, and changes during those years, is presented below:

	2014				2013				2012
	Shares		Weighted Average Grant Date Fair Value		Shares		Weighted Average Grant Date Fair Value		Shares		Weighted Average Grant Date Fair Value
Outstanding share awards at   January 1	259,841		$	50.87	392,655		$	44.67	749,538		$	19.52
Granted	54,379		105.08		124,513		63.46		150,865		40.24
Settled	—		—		(246,592	)	47.19		(499,680	)	5.65
Forfeited	(13,356	)	71.03		(10,735	)	54.87		(8,068	)	42.15
Outstanding share awards at   December 31	300,864		59.77		259,841		50.87		392,655		44.67
Aggregate intrinsic value (in   thousands)			$	20,624			$	13,642			$	15,376