Goodwill (Details) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2016	Dec. 31, 2015	Aug. 31, 2016	May 31, 2015	Apr. 01, 2015
Goodwill [Line Items]
Goodwill		$ 1,133,534,000	$ 287,393,000
Goodwill impairment		0	0
Talmer
Goodwill [Line Items]
Goodwill				$ 846,667,000
Goodwill acquired during period		$ 846,700,000
Lake Michigan
Goodwill [Line Items]
Goodwill			101,061,000		$ 101,061,000
Goodwill acquired during period	$ 600,000
Monarch
Goodwill [Line Items]
Goodwill			$ 5,339,000			$ 5,339,000