Share-Based Payment Arrangements (Tables)

12 Months Ended

Dec. 31, 2017

Share-Based Payment Arrangements [Abstract]

Summary of Option Activity

Options	Number of Shares	Weighted- Average Exercise Price ($)		Weighted- Average Remaining Contractual Term (Years)	Aggregate Intrinsic Value ($000)
Outstanding at January 1, 2017	456,258	$	35.91	3.5	$	3,734
Exercised	(350,744)		34.65			4,304
Cancelled/Forfeited	(538)		32.09			6
Expired	(16,675)		68.18			—
Outstanding at December 31, 2017	88,301	$	34.84	2.8	$	1,294
Exercisable at December 31, 2017	88,301	$	34.84	2.8	$	1,294

Summary of Nonvested Restricted and Performance Shares

	Number of Shares	Weighted- Average Grant-Date Fair Value ($)
Nonvested at January 1, 2017	2,152,119	$	32.12
Granted	525,258		45.71
Vested	(906,944)		30.66
Cancelled/Forfeited	(61,491)		32.57
Nonvested at December 31, 2017	1,708,942	$	37.05