Investment in Securities (Details) $ in Thousands | 3 Months Ended | 12 Months Ended |
Mar. 31, 2016USD ($)Security | Mar. 31, 2015USD ($) | Dec. 31, 2015USD ($)Security |
Available-for-sale debt securities, amortized cost basis [Abstract] | | | |
Amortized cost | $ 1,112,913 | | $ 1,088,258 |
Gross unrealized gains | 67,990 | | 46,474 |
Gross unrealized losses | (14) | | (1,087) |
Estimated fair value | 1,180,889 | | 1,133,645 |
Available-for-sale equity securities, amortized cost basis [Abstract] | | | |
Estimated fair value | 293,985 | | 197,071 |
Available-for-sale securities, amortized cost basis [Abstract] | | | |
Amortized cost | 1,372,651 | | 1,257,851 |
Gross unrealized gains | 103,124 | | 74,325 |
Gross unrealized losses | (901) | | (1,460) |
Estimated fair value | 1,474,874 | | 1,330,716 |
Securities held to maturity [Abstract] | | | |
Amortized cost | 2,929 | | 2,929 |
Gross unrealized gains | 231 | | 195 |
Gross unrealized losses | 0 | | 0 |
Estimated fair value | 3,160 | | 3,124 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract] | | | |
Less than 12 months, Estimated Fair Value | 37,067 | | 240,407 |
12 months or longer, Estimated Fair Value | 0 | | 0 |
Estimated Fair Value, Total | 37,067 | | 240,407 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract] | | | |
Less than 12 months, Gross Unrealized Loss | (901) | | (1,460) |
12 months or longer, Gross Unrealized Loss | 0 | | 0 |
Gross Unrealized Loss, Total | $ (901) | | $ (1,460) |
Available-for-sale, Securities in Unrealized Loss Positions, Number of Securities [Abstract] | | | |
Less than 12 months, Number of Securities | Security | 8 | | 29 |
12 months or longer, Number of Securities | Security | 0 | | 0 |
Number of Securities | Security | 8 | | 29 |
Fair value of the positions other-than-temporarily impaired | $ 0 | $ 1,202 | |
Securities available for sale, Amortized Cost [Abstract] | | | |
Due in one year or less, amortized cost | 54,942 | | |
Due after one year through five, amortized cost | 375,679 | | |
Due after five years through ten years, amortized cost | 112,592 | | |
Due after ten years, amortized cost | 547,191 | | |
Residential mortgage-backed securities, amortized cost | 826 | | |
Collateralized mortgage obligations, amortized cost | 21,683 | | |
Amortized cost | 1,112,913 | | $ 1,088,258 |
Securities available for sale, Estimated Fair Value [Abstract] | | | |
Due in one year or less, estimated fair value | 55,431 | | |
Due after one year through five, estimated fair value | 384,401 | | |
Due after five years through ten years, estimated fair value | 121,883 | | |
Due after ten years, estimated fair value | 596,373 | | |
Residential mortgage-backed securities, estimated fair value | 877 | | |
Collateralized mortgage obligations, estimated fair value | 21,924 | | |
Estimated fair value | 1,180,889 | | 1,133,645 |
Securities held to maturity, Amortized Cost [Abstract] | | | |
Due in one year or less, amortized cost | 2,118 | | |
Due after ten years, amortized cost | 620 | | |
Residential mortgage-backed securities, amortized cost | 191 | | |
Amortized cost | 2,929 | | 2,929 |
Securities held to maturity, Estimated Fair Value [Abstract] | | | |
Due in one year or less, estimated fair value | 2,118 | | |
Due after ten years, estimated fair value | 834 | | |
Residential mortgage-backed securities, estimated fair value | 208 | | |
Estimated fair value | 3,160 | | $ 3,124 |
Securities available for sale [Abstract] | | | |
Net realized gains on securities available for sale | 58 | 6,213 | |
Recognized in accumulated other comprehensive income [Abstract] | | | |
Available-for-sale Securities | 29,358 | 2,813 | |
Not recognized in the consolidated financial statements [Abstract] | | | |
Fixed maturities - held to maturity | 36 | 17 | |
Deferred tax liability on unrealized gains | $ 9,781 | 1,019 | |
Percentage of individual investment in securities to stockholders' equity | 10.00% | | 10.00% |
Obligation of Government-sponsored Enterprises [Member] | | | |
Available-for-sale debt securities, amortized cost basis [Abstract] | | | |
Amortized cost | $ 103,472 | | $ 115,965 |
Gross unrealized gains | 881 | | 301 |
Gross unrealized losses | 0 | | (26) |
Estimated fair value | 104,353 | | 116,240 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract] | | | |
Less than 12 months, Estimated Fair Value | | | 18,989 |
12 months or longer, Estimated Fair Value | | | 0 |
Estimated Fair Value, Total | | | 18,989 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract] | | | |
Less than 12 months, Gross Unrealized Loss | | | (26) |
12 months or longer, Gross Unrealized Loss | | | 0 |
Gross Unrealized Loss, Total | | | $ (26) |
Available-for-sale, Securities in Unrealized Loss Positions, Number of Securities [Abstract] | | | |
Less than 12 months, Number of Securities | Security | | | 1 |
12 months or longer, Number of Securities | Security | | | 0 |
Number of Securities | Security | | | 1 |
Securities available for sale, Amortized Cost [Abstract] | | | |
Amortized cost | 103,472 | | $ 115,965 |
Securities available for sale, Estimated Fair Value [Abstract] | | | |
Estimated fair value | 104,353 | | 116,240 |
U.S. Treasury Securities and Obligations of U.S. Government Instrumentalities [Member] | | | |
Available-for-sale debt securities, amortized cost basis [Abstract] | | | |
Amortized cost | 116,643 | | 163,322 |
Gross unrealized gains | 1,354 | | 234 |
Gross unrealized losses | 0 | | (286) |
Estimated fair value | 117,997 | | 163,270 |
Securities held to maturity [Abstract] | | | |
Amortized cost | 620 | | 620 |
Gross unrealized gains | 214 | | 178 |
Gross unrealized losses | 0 | | 0 |
Estimated fair value | 834 | | 798 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract] | | | |
Less than 12 months, Estimated Fair Value | | | 130,996 |
12 months or longer, Estimated Fair Value | | | 0 |
Estimated Fair Value, Total | | | 130,996 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract] | | | |
Less than 12 months, Gross Unrealized Loss | | | (286) |
12 months or longer, Gross Unrealized Loss | | | 0 |
Gross Unrealized Loss, Total | | | $ (286) |
Available-for-sale, Securities in Unrealized Loss Positions, Number of Securities [Abstract] | | | |
Less than 12 months, Number of Securities | Security | | | 5 |
12 months or longer, Number of Securities | Security | | | 0 |
Number of Securities | Security | | | 5 |
Securities available for sale, Amortized Cost [Abstract] | | | |
Amortized cost | 116,643 | | $ 163,322 |
Securities available for sale, Estimated Fair Value [Abstract] | | | |
Estimated fair value | 117,997 | | 163,270 |
Securities held to maturity, Amortized Cost [Abstract] | | | |
Amortized cost | 620 | | 620 |
Securities held to maturity, Estimated Fair Value [Abstract] | | | |
Estimated fair value | 834 | | 798 |
Obligations of The Commonwealth of Puerto Rico and Its Instrumentalities [Member] | | | |
Available-for-sale debt securities, amortized cost basis [Abstract] | | | |
Amortized cost | 25,636 | | 25,302 |
Gross unrealized gains | 782 | | 317 |
Gross unrealized losses | 0 | | 0 |
Estimated fair value | 26,418 | | 25,619 |
Securities available for sale, Amortized Cost [Abstract] | | | |
Amortized cost | 25,636 | | 25,302 |
Securities available for sale, Estimated Fair Value [Abstract] | | | |
Estimated fair value | 26,418 | | 25,619 |
Municipal Securities [Member] | | | |
Available-for-sale debt securities, amortized cost basis [Abstract] | | | |
Amortized cost | 642,621 | | 612,225 |
Gross unrealized gains | 48,559 | | 35,418 |
Gross unrealized losses | 0 | | (197) |
Estimated fair value | 691,180 | | 647,446 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract] | | | |
Less than 12 months, Estimated Fair Value | | | 43,937 |
12 months or longer, Estimated Fair Value | | | 0 |
Estimated Fair Value, Total | | | 43,937 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract] | | | |
Less than 12 months, Gross Unrealized Loss | | | (197) |
12 months or longer, Gross Unrealized Loss | | | 0 |
Gross Unrealized Loss, Total | | | $ (197) |
Available-for-sale, Securities in Unrealized Loss Positions, Number of Securities [Abstract] | | | |
Less than 12 months, Number of Securities | Security | | | 11 |
12 months or longer, Number of Securities | Security | | | 0 |
Number of Securities | Security | | | 11 |
Securities available for sale, Amortized Cost [Abstract] | | | |
Amortized cost | 642,621 | | $ 612,225 |
Securities available for sale, Estimated Fair Value [Abstract] | | | |
Estimated fair value | 691,180 | | 647,446 |
Corporate Bonds [Member] | | | |
Available-for-sale debt securities, amortized cost basis [Abstract] | | | |
Amortized cost | 202,032 | | 148,198 |
Gross unrealized gains | 16,121 | | 9,782 |
Gross unrealized losses | (13) | | (572) |
Estimated fair value | 218,140 | | 157,408 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract] | | | |
Less than 12 months, Estimated Fair Value | 5,284 | | 35,718 |
12 months or longer, Estimated Fair Value | 0 | | 0 |
Estimated Fair Value, Total | 5,284 | | 35,718 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract] | | | |
Less than 12 months, Gross Unrealized Loss | (13) | | (572) |
12 months or longer, Gross Unrealized Loss | 0 | | 0 |
Gross Unrealized Loss, Total | $ (13) | | $ (572) |
Available-for-sale, Securities in Unrealized Loss Positions, Number of Securities [Abstract] | | | |
Less than 12 months, Number of Securities | Security | 1 | | 9 |
12 months or longer, Number of Securities | Security | 0 | | 0 |
Number of Securities | Security | 1 | | 9 |
Securities available for sale, Amortized Cost [Abstract] | | | |
Amortized cost | $ 202,032 | | $ 148,198 |
Securities available for sale, Estimated Fair Value [Abstract] | | | |
Estimated fair value | 218,140 | | 157,408 |
Residential Mortgage-backed Securities [Member] | | | |
Available-for-sale debt securities, amortized cost basis [Abstract] | | | |
Amortized cost | 826 | | 883 |
Gross unrealized gains | 51 | | 54 |
Gross unrealized losses | 0 | | 0 |
Estimated fair value | 877 | | 937 |
Securities held to maturity [Abstract] | | | |
Amortized cost | 191 | | 191 |
Gross unrealized gains | 17 | | 17 |
Gross unrealized losses | 0 | | 0 |
Estimated fair value | 208 | | 208 |
Securities available for sale, Amortized Cost [Abstract] | | | |
Amortized cost | 826 | | 883 |
Securities available for sale, Estimated Fair Value [Abstract] | | | |
Estimated fair value | 877 | | 937 |
Securities held to maturity, Amortized Cost [Abstract] | | | |
Amortized cost | 191 | | 191 |
Securities held to maturity, Estimated Fair Value [Abstract] | | | |
Estimated fair value | 208 | | 208 |
Collateralized Mortgage Obligations [Member] | | | |
Available-for-sale debt securities, amortized cost basis [Abstract] | | | |
Amortized cost | 21,683 | | 22,363 |
Gross unrealized gains | 242 | | 368 |
Gross unrealized losses | (1) | | (6) |
Estimated fair value | 21,924 | | 22,725 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract] | | | |
Less than 12 months, Estimated Fair Value | 1,292 | | 1,448 |
12 months or longer, Estimated Fair Value | 0 | | 0 |
Estimated Fair Value, Total | 1,292 | | 1,448 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract] | | | |
Less than 12 months, Gross Unrealized Loss | (1) | | (6) |
12 months or longer, Gross Unrealized Loss | 0 | | 0 |
Gross Unrealized Loss, Total | $ (1) | | $ (6) |
Available-for-sale, Securities in Unrealized Loss Positions, Number of Securities [Abstract] | | | |
Less than 12 months, Number of Securities | Security | 1 | | 1 |
12 months or longer, Number of Securities | Security | 0 | | 0 |
Number of Securities | Security | 1 | | 1 |
Securities available for sale, Amortized Cost [Abstract] | | | |
Amortized cost | $ 21,683 | | $ 22,363 |
Securities available for sale, Estimated Fair Value [Abstract] | | | |
Estimated fair value | 21,924 | | 22,725 |
Fixed Maturities [Member] | | | |
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract] | | | |
Less than 12 months, Estimated Fair Value | 6,576 | | 231,088 |
12 months or longer, Estimated Fair Value | 0 | | 0 |
Estimated Fair Value, Total | 6,576 | | 231,088 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract] | | | |
Less than 12 months, Gross Unrealized Loss | (14) | | (1,087) |
12 months or longer, Gross Unrealized Loss | 0 | | 0 |
Gross Unrealized Loss, Total | $ (14) | | $ (1,087) |
Available-for-sale, Securities in Unrealized Loss Positions, Number of Securities [Abstract] | | | |
Less than 12 months, Number of Securities | Security | 2 | | 27 |
12 months or longer, Number of Securities | Security | 0 | | 0 |
Number of Securities | Security | 2 | | 27 |
Securities available for sale [Abstract] | | | |
Gross gains from sales | $ 961 | 4,009 | |
Gross losses from sales | (1,359) | (275) | |
Gross losses from other-than-temporary impairments | 0 | (1,202) | |
Total fixed maturity securities | (398) | 2,532 | |
Recognized in accumulated other comprehensive income [Abstract] | | | |
Available-for-sale Securities | 22,589 | 4,091 | |
Mutual Funds [Member] | | | |
Available-for-sale equity securities, amortized cost basis [Abstract] | | | |
Amortized cost | 259,738 | | $ 169,593 |
Gross unrealized gains | 35,134 | | 27,851 |
Gross unrealized losses | (887) | | (373) |
Estimated fair value | 293,985 | | 197,071 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract] | | | |
Less than 12 months, Estimated Fair Value | 30,491 | | 9,319 |
12 months or longer, Estimated Fair Value | 0 | | 0 |
Estimated Fair Value, Total | 30,491 | | 9,319 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract] | | | |
Less than 12 months, Gross Unrealized Loss | (887) | | (373) |
12 months or longer, Gross Unrealized Loss | 0 | | 0 |
Gross Unrealized Loss, Total | $ (887) | | $ (373) |
Available-for-sale, Securities in Unrealized Loss Positions, Number of Securities [Abstract] | | | |
Less than 12 months, Number of Securities | Security | 6 | | 2 |
12 months or longer, Number of Securities | Security | 0 | | 0 |
Number of Securities | Security | 6 | | 2 |
Equity Securities [Member] | | | |
Securities available for sale [Abstract] | | | |
Gross gains from sales | $ 587 | 3,736 | |
Gross losses from sales | (131) | (55) | |
Total equity securities | 456 | 3,681 | |
Recognized in accumulated other comprehensive income [Abstract] | | | |
Available-for-sale Securities | 6,769 | (1,278) | |
Certificates of Deposit [Member] | | | |
Securities held to maturity [Abstract] | | | |
Amortized cost | 2,118 | | $ 2,118 |
Gross unrealized gains | 0 | | 0 |
Gross unrealized losses | 0 | | 0 |
Estimated fair value | 2,118 | | 2,118 |
Securities held to maturity, Amortized Cost [Abstract] | | | |
Amortized cost | 2,118 | | 2,118 |
Securities held to maturity, Estimated Fair Value [Abstract] | | | |
Estimated fair value | 2,118 | | $ 2,118 |
Escrow Bonds [Member] | | | |
Available-for-sale debt securities, amortized cost basis [Abstract] | | | |
Estimated fair value | 16,306 | | |
Available-for-sale securities, amortized cost basis [Abstract] | | | |
Gross unrealized gains | 46 | | |
Securities available for sale, Estimated Fair Value [Abstract] | | | |
Estimated fair value | 16,306 | | |
Cofina Bonds [Member] | | | |
Available-for-sale debt securities, amortized cost basis [Abstract] | | | |
Estimated fair value | 10,112 | | |
Available-for-sale securities, amortized cost basis [Abstract] | | | |
Gross unrealized gains | 736 | | |
Available-for-sale, Securities in Unrealized Loss Positions, Number of Securities [Abstract] | | | |
Fair value of the positions other-than-temporarily impaired | 0 | $ 1,202 | |
Securities available for sale, Estimated Fair Value [Abstract] | | | |
Estimated fair value | $ 10,112 | | |