Goodwill and intangibles (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Goodwill [Line Items]
Goodwill	$ 137,889,000	$ 137,889,000
Goodwill, impairment loss	0	0
Carrying value of intangibles	31,700,000	31,700,000
Trademarks and Trade Name
Goodwill [Line Items]
Carrying value of intangibles	31,700,000
Impairment of intangible assets, indefinite-lived	0	$ 0
PCD
Goodwill [Line Items]
Goodwill	$ 137,900,000