Accumulated Other Comprehensive Income (Loss) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Increase (decrease) in accumulated other comprehensive income (loss) [Roll Forward]
Balance at the beginning of the year	$ (7,115)	$ (6,344)	$ (3,072)
Unrealized gains (losses)	(1,864)	561	(509)
Unrealized gains in fair value	0	123	917
Amounts reclassified from accumulated other comprehensive income (loss)	1,401	1,268	481
Tax effect	(532)	(507)	(184)
Unrecognized amounts from defined benefit pension plans	6,306	(3,712)	(6,592)
Tax effect	(2,589)	1,496	2,615
Net of tax amount	2,722	(771)	(3,272)
Balance at the end of the year	(4,393)	(7,115)	(6,344)
Foreign Currency Translation Adjustments
Increase (decrease) in accumulated other comprehensive income (loss) [Roll Forward]
Balance at the beginning of the year	3,511	2,950	3,459
Unrealized gains (losses)	(1,864)	561	(509)
Unrealized gains in fair value	0	0	0
Amounts reclassified from accumulated other comprehensive income (loss)	0	0	0
Tax effect	0	0	0
Unrecognized amounts from defined benefit pension plans	0	0	0
Tax effect	0	0	0
Net of tax amount	(1,864)	561	(509)
Balance at the end of the year	1,647	3,511	2,950
Interest Rate Cash Flow Hedges
Increase (decrease) in accumulated other comprehensive income (loss) [Roll Forward]
Balance at the beginning of the year	0	(77)	(645)
Unrealized gains (losses)	0	0	0
Unrealized gains in fair value	0	123	917
Amounts reclassified from accumulated other comprehensive income (loss)	0	0	0
Tax effect	0	0	0
Unrecognized amounts from defined benefit pension plans	0	0	0
Tax effect	0	(46)	(349)
Net of tax amount	0	77	568
Balance at the end of the year	0	0	(77)
Defined Benefit Pension Plans
Increase (decrease) in accumulated other comprehensive income (loss) [Roll Forward]
Balance at the beginning of the year	(10,626)	(9,217)	(5,886)
Unrealized gains (losses)	0	0	0
Unrealized gains in fair value	0	0	0
Amounts reclassified from accumulated other comprehensive income (loss)	1,401	1,268	481
Tax effect	(532)	(507)	(184)
Unrecognized amounts from defined benefit pension plans	6,306	(3,712)	(6,592)
Tax effect	(2,589)	1,542	2,964
Net of tax amount	4,586	(1,409)	(3,331)
Balance at the end of the year	$ (6,040)	$ (10,626)	$ (9,217)