Share-Based Transactions (Tables)

12 Months Ended

Dec. 31, 2017

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity

The following table summarizes employee and director restricted stock and RSU activity during the years ended December 31, 2017, 2016, and 2015.

	Shares			Weighted-average measurement-date fair value per share
	(Shares in thousands)
Unvested employee and director restricted stock and RSUs, December 31, 2014		580		$	34.67
Granted		246			52.75
Forfeited		(8	)		41.98
Vested		(428	)		35.43
Unvested employee and director restricted stock and RSUs, December 31, 2015		390			45.07
Granted		225			42.86
Forfeited		-			-
Vested		(219	)		42.28
Unvested employee and director RSUs, December 31, 2016		396			45.37
Granted		130			80.33
Forfeited		(1	)		57.53
Vested		(213	)		46.54
Unvested employee and director RSUs, December 31, 2017		312		$	59.10

Schedule of Share-Based Transactions, PSU Activity

The following table summarizes PSU activity during the years ended December 31, 2017 and 2016.

	Shares		Weighted-average measurement-date fair value per share
	(Shares in thousands)
Unvested employee PSUs, December 31, 2015		-	n/a
Granted		18	$	41.88
Forfeited		-		-
Vested		-		-
Unvested employee PSUs, December 31, 2016		18		41.88
Granted		36		80.45
Forfeited		-		-
Vested		-		-
Unvested employee PSUs, December 31, 2017		54	$	67.42

Summary of Activity Related to Stock Options Outstanding and Exercisable

The following table summarizes activity related to stock options outstanding and exercisable during the years ended December 31, 2017, 2016, and 2015:

	Outstanding					Exercisable
	Number of shares			Weighted average exercise price		Number of shares		Weighted average exercise price
	(Shares in thousands)
Outstanding at December 31, 2014		246		$	36.67		40	$	32.63
Granted		46			53.50
Exercised		(89	)		34.89
Outstanding at December 31, 2015		203			41.28		35		36.38
Granted		90			41.88
Exercised		(148	)		38.24
Outstanding at December 31, 2016		145			44.75		6		53.50
Granted		-			-
Exercised		(38	)		43.63
Outstanding at December 31, 2017		107			45.15		32	$	47.26
Range of granted option exercise prices outstanding at December 31, 2017
$41.20 (average term remaining - 6.1 years)		7		$	41.20		7	$	41.20
$53.50 (average term remaining - 7.2 years)		31			53.50		15		53.50
$41.88 (average term remaining - 8.2 years)		69			41.88		9		41.88

Summary of Intrinsic Values of Stock Options

A summary of the intrinsic values of our stock options is as follows:

	December 31, 2017
	(In thousands)
Aggregate intrinsic value of exercisable stock options	$	1,714
Aggregate intrinsic value of stock options expected to vest		4,302
Aggregate intrinsic value of stock options outstanding	$	6,016

Summary of Intrinsic Value, Tax Benefit Realized and Value of Shares Withheld Related to Option Exercise Activity

The intrinsic value, tax benefit realized and value of shares withheld related to option exercise activity are summarized as follows:

	Year ended December 31,
	2017		2016		2015
	(In thousands)
Intrinsic value of options exercised	$	1,453	$	2,755	$	1,620
Tax benefit realized from the options exercised		509		964		567
Value of issued shares withheld to satisfy option    exercise price		1,673		5,509		2,966

Schedule of Share-based Goods and Nonemployee Services Transaction by Supplier

The following table summarizes non-employee RSU activity during the years ended December 31, 2017, 2016, and 2015.

	Shares			Weighted-average measurement-date fair value per share
	(Shares in thousands)
Unvested non-employee RSUs, December 31, 2014		73		$	49.98
Granted		326			42.79
Vested		(326	)		44.39
Unvested non-employee RSUs, December 31, 2015		73			42.83
Granted		236			48.45
Vested		(267	)		44.82
Unvested non-employee RSUs, December 31, 2016		42			61.55
Granted		156			75.69
Vested		(166	)		68.96
Unvested non-employee RSUs, December 31, 2017		32		$	91.88

Schedule of Share-based Compensation, Restricted Stock Units Award Activity

The following table presents the assumptions used in valuing quarterly RSU grants to agents:

	Year ended December 31,
	2017	2016	2015
Expected volatility	18% to 34%	24% to 42%	18% to 35%
Quarterly dividends expected	$0.19 to $0.20	$0.17 to $0.18	$	0.16
Risk-free interest rates	Less than 3%	Less than 2%	Less than 2%

Schedule of Compensation Cost and Tax Benefits for Share Based Payment Arrangements Nonemployee Equity Awards

Details on the granting and valuation of these awards were as follows:

	Year ended December 31,
	2017			2016		2015
	(Dollars in thousands, except per-share amounts)
Total quarterly non-employee RSUs granted		155,996			235,735		325,744
Measurement date per-share fair value of awards	$67.82 to $91.88			$39.87 to $61.50		$40.98 to $46.71
Illiquidity discounts		10	%	10% to 11%		8% to 9%
Quarterly incentive awards expense recognized currently	$	980		$	910	$	466
Quarterly incentive awards expense deferred		10,821			10,517		13,423
Tax benefit associated with incentive awards		2,259			3,674		4,454

Restricted stock units (RSUs) [Member] | Employee and Director [Member]

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Schedule of Share-Based Compensation, Recognized Expense and Tax Benefit Offsets

We recognized expense and tax benefit offsets as follows for employee and director share-based compensation:

	Year ended December 31,
	2017		2016		2015
	(In thousands)
Total equity awards expense recognized	$	11,364	$	11,067	$	13,839
Tax benefit associated with total employee and director   share-based compensation		1,893		3,715		4,668

Performance share units (PSUs) [Member] | Employee [Member]

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Schedule of Share-Based Compensation, Recognized Expense and Tax Benefit Offsets

In connection with our granting of PSU awards, we recognized expense and tax benefit offsets as follows:

	Year ended December 31,
	2017		2016		2015
	(In thousands)
Total employee PSU award expense	$	2,761	$	614	n/a
Tax benefit associated with total employee PSU award expense		187		215	n/a

Employee Stock Option [Member]

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Schedule of Share-Based Compensation, Recognized Expense and Tax Benefit Offsets

Compensation expense and related tax benefits recognized for stock option awards were as follows:

	Year ended December 31,
	2017		2016		2015
	(In thousands)
Expense recognized for stock option awards	$	162	$	851	$	643
Tax benefit recognized for stock option awards		37		298		225