Stock-based compensation (Tables)

9 Months Ended

Sep. 30, 2017

Executive Officers

Schedule of Unvested Restricted Stock Units Roll Forward [Table Text Block]

(Not in thousands)	Shares		Weighted-Average Grant Date Fair Value
Non-vested at December 31, 2015	495,731	$	28.25
Granted	344,488		25.86
Quantity adjusted by TSR factor	39,566		24.37
Vested	(487,784)		27.72
Forfeited	(8,019)		29.13
Non-vested at December 31, 2016	383,982	$	26.35
Granted	212,200		42.57
Quantity adjusted by TSR factor	(39,414)		33.77
Vested	(188,399)		35.47
Non-vested at September 30, 2017	368,369	$	30.24

Directors

Schedule of Unvested Restricted Stock Units Roll Forward [Table Text Block]

(Not in thousands)	Restricted Stock		Weighted-Average Grant Date Fair Value
Non-vested at December 31, 2015	-	$	-
Granted	40,517		29.77
Vested	(40,517)		29.77
Forfeited	-		-
Non-vested at December 31, 2016	-	$	-
Granted	25,771		38.42
Vested	(25,771)		38.42
Forfeited	-		-
Non-vested at September 30, 2017	-	$	-