Retirement Plans (Changes in Accumulated Other Comprehensive Income (Loss) Related to Retirement Plans) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated other comprehensive income (loss) at beginning of year	$ (32,243)	$ (18,040)
Prior service credits	81
Net actuarial gain (loss)	5,018
Change in adjustment for pension and other postretirement benefits, net of tax benefit (expense) of $(2,746), $7,648, and $(9,344) for the years ended December 31, 2015, 2014, and 2013, respectively	5,099	(14,203)	$ 17,353
Accumulated other comprehensive income (loss) at end of year	(27,144)	(32,243)	$ (18,040)
Pension Plan [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated other comprehensive income (loss) at beginning of year	(31,853)
Prior service credits	(3)
Net actuarial gain (loss)	4,565
Change in adjustment for pension and other postretirement benefits, net of tax benefit (expense) of $(2,746), $7,648, and $(9,344) for the years ended December 31, 2015, 2014, and 2013, respectively	4,562
Accumulated other comprehensive income (loss) at end of year	(27,291)	(31,853)
Postretirement Plan [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated other comprehensive income (loss) at beginning of year	83
Prior service credits	84
Net actuarial gain (loss)	235
Change in adjustment for pension and other postretirement benefits, net of tax benefit (expense) of $(2,746), $7,648, and $(9,344) for the years ended December 31, 2015, 2014, and 2013, respectively	319
Accumulated other comprehensive income (loss) at end of year	402	83
Supplemental Plan [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated other comprehensive income (loss) at beginning of year	(473)
Prior service credits	0
Net actuarial gain (loss)	218
Change in adjustment for pension and other postretirement benefits, net of tax benefit (expense) of $(2,746), $7,648, and $(9,344) for the years ended December 31, 2015, 2014, and 2013, respectively	218
Accumulated other comprehensive income (loss) at end of year	$ (255)	$ (473)