v3.7.0.1
Earnings per Common Share Basic Earnings Per Share (Details) - USD ($)
$ / shares in Units, shares in Thousands, $ in Thousands
3 Months Ended
Mar. 31, 2017
Mar. 31, 2016
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]    
Net income $ 40,754 $ 32,882
Income attributable to preferred stock 0 (972)
Net income allocated to Class A common stockholders $ 40,754 $ 31,910
Weighted-average Class A shares issued and outstanding 50,458 49,863
Basic earnings per Class A common share, in usd per share $ 0.81 $ 0.64
Re-allocated earnings $ 0 $ 19
Diluted net income allocated to Class A common stockholders $ 40,754 $ 31,929
Diluted weighted-average Class A shares issued and outstanding 52,497 50,867
Diluted earnings per Class A common share, in usd per share $ 0.78 $ 0.63
Stock Options [Member]    
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]    
Dilutive potential common shares 603 343
Restricted Stock Units (RSUs) [Member]    
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]    
Dilutive potential common shares 1,417 630
Employee Stock Purchase Plan [Member]    
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]    
Dilutive potential common shares 19 31
Common Class A [Member]    
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]    
Weighted-average Class A shares issued and outstanding 50,458 49,863
Basic earnings per Class A common share, in usd per share $ 0.81 $ 0.64
Diluted weighted-average Class A shares issued and outstanding 52,497 50,867
Diluted earnings per Class A common share, in usd per share $ 0.78 $ 0.63