Property and Equipment, net - Narrative (Details) - USD ($)
$ in Thousands |
12 Months Ended |
Dec. 31, 2015 |
Dec. 31, 2014 |
Dec. 31, 2013 |
| Property, Plant and Equipment [Line Items] |
|
|
|
| Capitalized amount related to premises |
$ 101,001
|
$ 50,655
|
|
| Accumulated amortization |
29,611
|
19,924
|
|
| Lease financing obligation |
28,900
|
6,600
|
|
| Property and equipment capitalized but not placed in service |
5,300
|
8,100
|
|
| Total depreciation and amortization expense |
17,646
|
13,213
|
$ 11,569
|
| Capitalized Facility Lease |
|
|
|
| Property, Plant and Equipment [Line Items] |
|
|
|
| Capitalized amount related to premises |
39,154
|
6,599
|
|
| Interest costs capitalized related to premises |
2,000
|
0
|
|
| Accumulated amortization |
200
|
|
|
| Property and equipment capitalized but not placed in service |
|
6,600
|
|
| Amortization of internal use capitalized software development costs |
200
|
|
|
| Property and Equipment |
|
|
|
| Property, Plant and Equipment [Line Items] |
|
|
|
| Total depreciation and amortization expense |
13,500
|
8,900
|
6,400
|
| Software Development |
|
|
|
| Property, Plant and Equipment [Line Items] |
|
|
|
| Amortization of internal use capitalized software development costs |
$ 8,800
|
$ 5,700
|
$ 3,800
|