Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2014

Summary of Activity for Non-voting Time-vested Restricted Stock

The following table summarizes the activity for non-voting time-vested restricted stock units granted to non-employee directors for the year ended December 31, 2014.

	Share Units			Weighted Average Grant-Date Fair Value			Remaining Average Contractual Life (in years)		Aggregate Value (in thousands)
Outstanding at January 1, 2014		3,048		$	38.44			2.85	$	117
Granted		2,202			44.04
Forfeited		—			—
Vested and released to participants		(762	)		(38.44	)
Outstanding at December 31, 2014		4,488		$	41.19			2.48	$	185

Non-Voting Time-Vested Restricted Stock Units [Member]

Summary of Activity for Non-voting Time-vested Restricted Stock

The following table summarizes the activity for non-voting time-vested restricted stock units granted to employees for the year ended December 31, 2014.

	Share Units			Weighted Average Grant-Date Fair Value			Remaining Average Contractual Life (in years)		Aggregate Value (in thousands)
Outstanding at January 1, 2014		61,258		$	24.11			1.65	$	1,477
Granted		142,726			43.25
Forfeited		—			—
Vested and released to participants		(12,329	)		(21.05	)
Outstanding at December 31, 2014		191,655		$	38.56			2.26	$	7,391

Non-Voting Performance Units [Member]

Summary of Activity for Non-voting Time-vested Restricted Stock

The following table summarizes the activity for non-voting performance-based restricted stock units for the year ended December 31, 2014.

	Share Units		Weighted Average Grant-Date Fair Value		Remaining Average Contractual Life (in years)		Aggregate Value (in thousands)
Outstanding at January 1, 2014		277,026	$	24.55		3.41	$	6,812
Granted		117,643		43.07
Forfeited		—		—
Vested and released to participants		—		—
Outstanding at December 31, 2014		394,669	$	30.07		1.78	$	11,878