Segment Reporting (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2016 USD ($) segment	Jun. 30, 2015 USD ($)	Dec. 31, 2015 USD ($)
Segment Reporting [Abstract]
Number of operating segments | segment			2
Segment Reporting Information [Line Items]
Net interest income	$ 73,118	$ 57,644	$ 145,825	$ 111,574
Provision for loan losses	2,118	5,674	4,185	7,345
Total noninterest income	31,026	30,661	60,604	61,324
Total noninterest expense	71,020	63,482	141,329	123,096
Income (loss) before taxes	31,006	19,149	60,915	42,457
Average Loans, for the period	5,582,878	4,447,124	5,470,490	4,357,855
Segment Assets, at period end	8,204,401	6,717,007	8,204,401	6,717,007	$ 7,694,754
Operating Segments | Community and Other Banking
Segment Reporting Information [Line Items]
Net interest income	71,895	55,988	143,478	108,877
Provision for loan losses	2,118	5,674	4,185	7,345
Total noninterest income	19,899	15,603	38,436	32,664
Total noninterest expense	59,694	48,987	119,433	96,446
Income (loss) before taxes	29,982	16,930	58,296	37,750
Average Loans, for the period	5,507,542	4,340,289	5,401,867	4,265,624
Segment Assets, at period end	8,082,153	6,579,225	8,082,153	6,579,225
Operating Segments | Retail Mortgage Banking
Segment Reporting Information [Line Items]
Net interest income	1,223	1,656	2,347	2,697
Provision for loan losses	0	0	0	0
Total noninterest income	11,127	15,058	22,168	28,660
Total noninterest expense	11,326	14,495	21,896	26,650
Income (loss) before taxes	1,024	2,219	2,619	4,707
Average Loans, for the period	75,336	106,835	68,623	92,231
Segment Assets, at period end	$ 122,248	$ 137,782	$ 122,248	$ 137,782