Goodwill (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Sep. 30, 2014	Sep. 30, 2012
Goodwill [Line Items]
Highest goodwill balance among other reporting units				$ 5,700,000
Average goodwill balance among other reporting units				800,000
Number of reporting units with allocated goodwill balances				215
Goodwill Carrying Value - UK Reporting Unit					6,900,000
Goodwill impairment	0	0	6,946,000
Goodwill [Roll Forward]
Balance, beginning of period	181,240,000	179,249,000
Acquired goodwill	3,907,000
Goodwill, Translation Adjustments	(1,957,000)	1,991,000
Balance, end of period	183,190,000	181,240,000	179,249,000
Accumulated goodwill impairment losses	(9,266,000)	(9,266,000)
Goodwill impairment	0	0	(6,946,000)
Accumulated goodwill impairment losses	(9,266,000)	(9,266,000)	(9,266,000)
Goodwill	$ 173,924,000	$ 171,974,000