Summary of Significant Accounting Policies (Earnings per Share) (EPS Calculations) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Accounting Policies [Abstract]
Anti-dilutive securities, options to purchase common stock outstanding (in shares)	10,846	24,783	23,954	13,877
Calculation of basic EPS:
Net income	$ 89,600	$ 33,229	$ 195,613	$ 98,349
Less: Net income allocated to participating securities	(184)	(135)	(489)	(399)
Net income attributable to common shareholders	$ 89,416	$ 33,094	$ 195,124	$ 97,950
Weighted-average common shares outstanding	205,826,000	114,540,000	168,955,000	114,182,000
Basic EPS (in dollars per share)	$ 0.43	$ 0.29	$ 1.15	$ 0.86
Calculation of diluted EPS:
Net income	$ 89,600	$ 33,229	$ 195,613	$ 98,349
Diluted weighted-average common shares outstanding	207,876,000	118,763,000	171,549,000	118,892,000
Diluted EPS (in dollars per share)	$ 0.43	$ 0.28	$ 1.14	$ 0.83