Goodwill and Other Intangible Assets - Summary of gross carrying amounts - (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Other intangible assets
Gross carrying amount	$ 82,154	$ 75,354	$ 82,154
Accumulated amortization	(36,633)	(28,131)	(34,729)
Net carrying amount	45,521	47,223	$ 47,425
Amortization expense	1,904	2,016
Amortization expense	1,900	$ 2,000
Estimated amortization expense for other intangibles for each of the next five quarters
June 30, 2016	1,892
September 30, 2016	1,891
December 31, 2016	1,891
March 31, 2017	1,810
June 30, 2017	1,798
Thereafter	$ 36,239
Minimum
Other intangible assets
Estimated useful lives	2 years
Maximum
Other intangible assets
Estimated useful lives	15 years