Retirement Plans (Changes in Accumulated Other Comprehensive Income (Loss) Related to Retirement Plans) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated other comprehensive income (loss) at beginning of year	$ (18,040)	$ (35,393)
Prior service credits	83
Net actuarial gain (loss)	(14,286)
Change in adjustment for pension and other postretirement benefits, net of tax benefit (expense) of $7,648, $(9,344), and $3,623 for the years ended December 31, 2014, 2013, and 2012, respectively	(14,203)	17,353	(6,728)
Accumulated other comprehensive income (loss) at end of year	(32,243)	(18,040)	(35,393)
Pension Plan [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated other comprehensive income (loss) at beginning of year	(17,979)
Prior service credits	(1)
Net actuarial gain (loss)	(13,873)
Change in adjustment for pension and other postretirement benefits, net of tax benefit (expense) of $7,648, $(9,344), and $3,623 for the years ended December 31, 2014, 2013, and 2012, respectively	(13,874)
Accumulated other comprehensive income (loss) at end of year	(31,853)
Postretirement Plan [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated other comprehensive income (loss) at beginning of year	269
Prior service credits	84
Net actuarial gain (loss)	(270)
Change in adjustment for pension and other postretirement benefits, net of tax benefit (expense) of $7,648, $(9,344), and $3,623 for the years ended December 31, 2014, 2013, and 2012, respectively	(186)
Accumulated other comprehensive income (loss) at end of year	83
Supplemental Plan [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated other comprehensive income (loss) at beginning of year	(330)
Prior service credits	0
Net actuarial gain (loss)	(143)
Change in adjustment for pension and other postretirement benefits, net of tax benefit (expense) of $7,648, $(9,344), and $3,623 for the years ended December 31, 2014, 2013, and 2012, respectively	(143)
Accumulated other comprehensive income (loss) at end of year	$ (473)