Goodwill and Other Intangible Assets - Summary of gross carrying amounts - (Details 2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Other intangible assets
Gross carrying amount	$ 82,154	$ 75,354
Accumulated amortization	(34,729)	(26,115)
Net carrying amount	47,425	49,239
Amortization expense	8,324	$ 8,320	$ 6,081
Estimated amortization expense for other intangibles for each of the next five years
2016	7,577
2017	7,202
2018	6,729
2019	6,330
2020	5,792
Thereafter	13,795
Total estimated amortization expense for other intangibles for the next five years	$ 47,425
Minimum
Other intangible assets
Estimated useful lives	2 years
Maximum
Other intangible assets
Estimated useful lives	15 years