Gains from Mortgage Banking Activities (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
GAINS FROM MORTGAGE BANKING ACTIVITIES
Contractual loan origination related fees, net									$ 156,835	$ 125,468	$ 111,699
Fair value of expected net future cash flows from servicing recognized at commitment									142,420	103,410	97,115
Fair value of expected guaranty obligation recognized at commitment									(8,789)	(6,895)	(5,143)
Total gains from mortgage banking activities	$ 76,986	$ 70,810	$ 69,950	$ 72,720	$ 71,876	$ 63,280	$ 52,241	$ 34,586	$ 290,466	$ 221,983	$ 203,671